I have some experience of what you are describing and yes it really makes you feel stretched to the limit. It's good your SS can talk to you freely. We ended up with sole custody of SS when he was 12 b/c of his mom's awful behavior. She did the same things you described along with substance abuse and some felonies and more. It's good you are getting some help. I would encourage you to get a therapist for yourself so you have a safe space to vent. These stresses can be so demanding you feel like you're fading away and loosing yourself. Some times it feels like you are doing the most thankless job in the world.

For me there was no magic bullet that made it better. But there were a lot of little things that helped me endure. Therapy helped me realize I wasn't doing everything wrong in spite of how it felt. Journaling and talking to trusted friends who would keep things private helped me not lose control of my emotions and stay balanced. Carving out small windows of time to just have a date with my husband, drama free, helped a lot. Exercise, hiking helped with stress too. Personally being busy is good for me so I started back up on hobbies that were important to me. Time and energy are precious commodities in a family so I know you might not have any left for yourself. But please, find a way to get a little time for yourself regularly or you will get lost. Otherwise this drama will fill your whole life and you'll feel like you can't breath. You need to take care of yourself, then you will have the energy to take care of your family.

Remember your life is more than just this problem, you are a complete person with talents, qualities, and intrests that you should continue to embrace. Don't give up and don't loose your identity as you go through this storm.

my heart goes out to you- best wishes 

You are dealing with parental alienation (i.e. PAS) it sounds like and it's very difficult to deal with. Many of us here have experienced it or are now experiencing it.  Educate yourself and your husband now - there are ways to counteract it but it must be done immediately and consistently (limit those phone calls to a specific time and time limit - they are damaging and there's no reason she needs 24 hour access....this was/is a problem for us too).

Available on Amazon; this book tells the story from the adult kids view but is pertinent to a younger kid and the target parents. Amy J. Baker has a good website with more book options too!  Get reading!

Adult Children of Parental Alienation Syndrome: Breaking the Ties That Bind (Norton Professional Book)

Amy J. L. Baker

We didn't have quite the serious situation you do, but we had the 3 SKs move in, one at a time, over a 9- month period.  I already had my 2 bio kids here so that made 5 kids with 6 years from oldest to youngest, 15 down to 9. 

I totally recall the feeling of being swamped and overwhelmed.  Just the logistics were a lot but like you, we also had those emotional issues.  Why did Mom let me go so easily? Will I fit in at this new school?  How to stay loyal to Mom?  From my bios, will I get along with them if they live here all the time?  I don't like sharing Mom's attention. I'm sure you know what I mean.

I thankfully had started counseling about the time the first moved in.  That was a huge help.  I can honestly say it changed 7 lives.  One thing I regret is I think the kids might have overheard me venting about BM on the phone.  If I had it to do over, I'd watch that.

The therapy for the kids is an excellent move.  They need it.   One thing my counselor stressed was one-on-one time with DH daily.  When I tried to explain how hard that was, he said, "JRI, I don't care if its just a walk down the street".  He was right.

I'm 76 and looking back, it's still the most tumultuous period in my life.  We went thru everything imaginable but all 5 kids are launched, they're all in their 50s now.  BM mellowed out somewhat and was a doting, if still volatile, grandma.

Wishing you all the best.

Hi, Momcy.  I was thinking about you and am cicling back to stress the importance of taking care of yourself.  You are the most important person in the house.  Don't put off anything that will help you, physically, mentally or logistically.

I developed stomach issues and headaches.  In my mind, the SKs were the cause and I suffered along.  Counseling got me to seek medical help: ISB and migraines, both of which were treated successfully.  I regret that I didnt seek medical help sooner rather than stewing and resenting the SKs.  Yes, the stress probably contributed but wasnt the cause.  So Momcy, get any medical help early.

Mentally, the counseling for you is important.  You'll be glad you went.

Logistically, think what you can do to ease your day-to-day so you have the bandwidth to deal with it all.  I have nonchalant housekeeping standards to start with but I hired cleaning help along the way.  DH also stepped up to keep things going.  He was a 50's dad but learned how to do laundry.  He also took all the kids out at least one day each weekend to give me some alone time.  When the SKs complained about a meal, he doled out  fast food $, it was within walking distance.  What I'm saying is it's much more important to be rested and present to deal with an emotional issue than it is to keep a spotless home, do all that laundry yourself or stress about a child turning up their nose at a meal.

Bottom line: take special care of your irreplaceable self.

How exactly can someone be a good mother and a bad influence on her kids?

Time for the facts.  The younger one needs clarity that it is BM and her choices that forced the Judge to remove them from her custody.  Reviewing a CO with kids in an age appropriate manner  is a great tool for driving clarity on these types of situations IMHO.

Any manipulation by BM must be met with a firm dose of the facts.  

We adopted this methodology early in our blended family adventure and increased SS-28's exposure to the facts as he got older and his SpermClan became more manipulative.    Eventually he came to a place where he would research their bullshit for himself when they would try to spread some manipulative manure when he was on SpermLand visitation.  As he progressed through his minor teen years we would occasional find him in our home office going through the Custody/Visitation/Support file cabinets.  

Kids need to have the information at hand to be able to protect themselves from the lies and toxic manipulations of the shallow and polluted end of their gene pool if they are unfortunate enough to be cursed with one.  This grows even more important as kids transition into adulthood.  The toxicity never ends until the kid says enough is enough and puts the toxic and manipulative in their place.

In the case of my SS-28.  His view clarified as he progressed into his teen then launched into young adulthood.  He now pretty much has no interface with the SpermClan after they attempted to manipulate him into direct depositing part of his USAF pay to SpermGrandHag to help support his three younger also out of wedlock SpermIdiot spawned half sibs by two other baby mamas.  He shut that crap down pronto.

Of the 4 SpermIdiot spawn he is the only viable adult.  He is the eldest.  #2 is marginally functional, #3 is in prison, and #4 is following #3 closely.  #2 detests the SpermIdiot, my SS has nothing to do with him, and the youngest two worship him.

Facts are neither good nor bad, they are merely facts. And they are powerful.

Use them.

I know that egg shell feeling. Don't give into it. When our custody battle was in full swing I remember my stepchild telling me and my husband "I'm going to tell mum you made me eat my dinner" when I said she should at least try vegetables and "I'm going to tell mum you made me go to bed too early" when we gave her a reasonable bed time. Chances are you and your partner are great parents and the youngest and BM will try and use things against you no matter what you do. There is no use trying to walk on egg shells because if they can't embellish details they will just invent them. You'll drive yourself crazy trying to constantly anticipate the right way to say things and the potential conseqences. Also, if you feel conversations with the youngest are risky - don't do it. It sounds harsh but let her vent without offering any opinion. The best thing you can do to be strong for any legal battles is be emotionally stable and not defensive. You are acting protectively not defensively. Make sure you take a break and fill your cup too. It sounds corny but self care is important.