I apologize in advance for the length of this post, but I need some serious advice...

A little background info on me; I am a 24 year old female (25 at the end of this month), never been married & have no kids of my own. I have been at my current place of employment for three years & managed to purchase my first home on my own the day I turned 22. Needless to say, I have had a solid upbringing thanks to my mother & am very self-sufficient & driven. I have been dating my current boyfriend for just shy of a year now. He just turned 31 & was raised to be a very respectful & responsible man & shows it in our relationship. He has been married & divorced twice already; he fathered two children in his first marriage that live with their mother & have been adopted by her current husband. He doesn't mention them much, but I know it hurts him that his ex-wife kept them from him. He admits he didn't do everything in his power to try to be a part of their lives & he regrets that. He fathered a third child, who just turned 6, in his second marriage & has legal joint custody that is shared with his ex-wife. I knew from the beginning that he had a son & was eager to meet him. We planned the meeting approximately 6-7 months into our relationship so we had time to guarantee our relationship was working out & that he wasn't bringing me into his son's life prematurely. The meeting went very well & all interactions after that had been great........until recently.
The legal nightmare began the weekend after I had met my boyfriend's son. As a courtesy, my boyfriend had informed his ex-wife he would be introducing their son to me that weekend. I even had him offer for her to meet me prior to ease any tense feelings she may have had. I know if I had a child, I would absolutely want to meet someone who was going to be around him/her so much so I know what kind of person they were. Her response to my offer was, "I don't want anything to do with that b****." This was about 3 months ago & to this day, she has yet to meet me. We've never interacted at all. The same day my boyfriend took his son back to his ex's house after that weekend, he received a call from CPS informing him that a report had been filed against him that stated his son had bruises on his face due to my boyfriend allegedly "grabbing & squeezing [his son's] face because he had interrupted his video game." I was with him for the majority of the weekend & that never occurred, nor did his son have anything even resembling a bruise on his face the day he was dropped of at his mother's house. That evening, a police officer showed up at my boyfriend's apartment & informed him that his ex-wife had filed a Protection from Abuse order against him as well & that he was not able to see his son until their court date. My boyfriend got a lawyer, went to the court date, & all charges were dismissed. She had no pictures of the alleged bruises, no witnesses, absolutely no evidence whatsoever that my boyfriend harmed his son. Immediately after the case was dismissed, she stormed into the clerk's office & filed numerous other frivolous lawsuits, including a motion to amend their custody & a request for him to start paying child support. He was eventually ordered to pay child support, & has been since.
About a month ago, due to all the lawyer fees & child support my boyfriend was dishing money out for, we decided it was best if he moved into my house to live so we could get everything sorted out. He also switched from working night shift to working day shift at his job. He informed his ex of his address & schedule change the day it occurred & again, I had him offer to have her come to my house to meet me & see that I keep a clean home since her son would be staying there every other weekend now. Again, the offer was met with an unwarranted insult towards me. Following the first weekend his son spent with us at my house, my boyfriend received yet another call from CPS stating his ex had accused him of grabbing his son's arm & leaving a bruise. He had the bruise the day he arrived at our home (I saw it as well) & when my boyfriend asked how he got it, he told him it happened at Tae Kwon Do practice. His ex-wife's statement to CPS said the following: "After [his son] had been dropped off by his father at my home, [son] was acting very distant, which is unlike him. I asked him if everything was okay & he said 'yes'. I took him swimming & he didn't want to take his shirt off & asked me if he could just swim with it on, which I let him. When we arrived home, I told him he had to take his shirt off since it was wet & when he did, I discovered the bruise on the back of his arm. I asked him what happened & [son] said his dad grabbed his arm really hard because he had interrupted his video game to ask for a drink of water." Absolutely ridiculous. Again, the charge was dismissed following the court hearing. The next weekend my boyfriend was supposed to get his son, his ex refused to cooperate with him & said she didn't feel safe letting their son around him since he's so "violent & can't control his anger" (He rarely ever even raises his voice). The following week, he received 3 more court summons for cases filed against him as well; one for failure to pay child support, one for failure to notify the other parent of an address change, & failure to show up for visitation (the alleged dates were the ones he was denied visitation for by his ex). At this point, his ex even began showing up at my home late in the evening unannounced while my boyfriend was still at work & I was the only one home. I didn't recognize the car outside, so I didn't answer the door the first time she showed up. The second time she showed up, I again refused to answer the door since my boyfriend wasn't home & her & I have no business together. She proceeded to beat my front door with her fist for approximately 10 minutes before taking it upon herself to walk around my home & try to open two other doors. I immediately called my boyfriend & told him to relay a very simple message to her: Either she gets back in her car & leaves my property in the next 30 seconds, or I call the police & have her arrested for trespassing. Thankfully, she left & that was the last time she has shown up at my home (that I know of).
Fast-forward to their most recent court date: my boyfriend filed a motion to amend custody per his lawyer's recommendation, since he had text message & voice-recorded evidence to refute every single claim she had filed against him. The court case ended in my boyfriend's favor greatly. All charges against him were dropped & the judge had his ex completely figured out. Custody was amended to grant my boyfriend joint physical custody with the visitation order specifying that my boyfriend have his son on his days off work (up until this point, they had joint custody with the ex having primary physical custody). The judge further stated that should his ex refuse him visitation again, he was to immediately file a contempt of court charge against her & she would be incarcerated. THE VERY NEXT DAY was my boyfriend's day to get his son, & his ex denied him visitation. They had a meeting pre-scheduled at his son's school to discuss summer school options & they both agreed she would bring their son to the meeting & he would go with his father after the meeting was over. My boyfriend showed up to the meeting & his ex did not. When he texted her to ask where she was, she stated she was there & tried to get in, but the doors were locked, so she left (complete bullshit). He asked if they could meet somewhere else for him to pick up his son & she never responded. The following day, he texted her & stated he would be picking their son up from school that day & had already contacted the school to inform them. She told him that was fine. That afternoon when my boyfriend went to pick his son up, he was informed that his ex had pulled him out of school early, three hours prior with no explanation. He attempted to contact her to find out what was going on & why she did that & she did not respond. After an hour of waiting, he texted her informing her he was on his way to her home to pick him up because it was his visitation day. She responded with, "We aren't home." He asked where they were at so he could come get him & she texted him back, "I'm not married to you, I don't have to tell you s***." She finally gave in & told him where they were, & he picked his son up & brought him to our house. Instantly, I noticed a drastic change in his son's behavior. He was extremely mouthy & talked back to his father every time he was told to do something. When my boyfriend told him it was time to get a bath & go to bed, he had a complete meltdown & threw a tantrum. He kept screaming that he wanted his mom to come pick him up & that he was never coming to our house again. All because he was told to go get a bath. He went upstairs & my boyfriend followed him & discovered that he had one of those cell-phone/watch combo things & that he had called his mother crying & told her to come pick him up. My boyfriend took the watch from him & his ex immediately called him on his phone. He had her on speaker phone & she said, "I'm coming to pick him up because I hate hearing him cry & you're the reason he's upset." My boyfriend asked him where he got the phone & she informed him that she bought him his own cell phone because she wanted him to be able to call her at any time while he was with us because she doesn't trust us. HE'S SIX. HE DOES NOT NEED A PHONE OF HIS OWN. My boyfriend told her the cell phone was not allowed in this house again & that she was to keep it with her when he was with us. His son calmed down & went upstairs & finally got in the shower & went to bed after throwing another tantrum. At this point, it was close 10:30, & I was exhausted from working all day & had to be up extremely early again. When we finally laid down to relax, the doorbell rang. I went to the door expecting his ex, only to find that it was a local police officer doing a welfare check. She had called the police & told them she was in fear for her son's life. You've GOT to be kidding me. The officer spoke with my boyfriend & I together & we told him exactly what happened. He was very nice & understood exactly what she was pulling & agreed with us: He's a kid. That's what they do in divorced families, they learn to pit one parent against the other when they don't want to do something. I come from a divorced family & I can tell you, I used to pull the same crap when I was a child.
This was the final straw for me. I have been nothing but patient & understanding with this entire situation, & up until this point, have stayed out of the issues between my boyfriend & his ex. However, now the crap she's pulling is directly impacting me as well. Showing up at my home unannounced, having officers come over for welfare checks late at night when we're trying to sleep, etc. I know exactly what she's trying to do; she's trying to destroy our relationship & she's trying to portray my boyfriend as an unfit parent because she is seeking full custody since she is planning to move out-of-state in September. I refuse to put up with this disrespect from someone that I have extended nothing but kindness towards. Her son is also directly suffering from her refusal to cooperate & co-parent with my boyfriend, because it shows in his behavior. She buys him whatever he wants & does not enforce any rules because she is trying to be the "favorite parent". Additionally, he is almost entirely dependent upon others to do everything for him & when he is asked to do something by my boyfriend that we know for a fact he is more than capable of doing, he instantly starts screaming & crying & saying "I can't!". My guess is this behavior is enforced at his mother's home, since she does everything for him & coddles him. My boyfriend & I want to raise him to be self-sufficient & respectful of others & have a very similar parenting style (even though I'm not even legally a step-parent at this point).
Unfortunately, the events from the past few nights aren't able to be relayed to my boyfriend's lawyer due to him being out of the office until Tuesday. However, as someone who has no legal rights due to my boyfriend & I not being married, are there any options for me to be involved in the legal process of attempting to get full custody of my boyfriend's son? He needs stability in his life at such a young age & I really believe living with us permanently would provide him with the support & nurturing he needs. Additionally, I do not want to create an even more volatile situation with the ex, but I need her to understand that she is not welcome on my property UNLESS we have all agreed that she would pick up or drop off her son at my home. I feel like she feels empowered right now by calling all the shots without input from anyone else the decisions impact & that needs to stop. Any advice for what I should do or what my role should be in this process would be extremely appreciated, because I have never dealt with any situation quite like this before & I'm not sure what our best course of action concerning my involvement should be. Thank you!