Overreacting? The woman told him, point blank, that she still loves him and wants him back.

I would not talk to the BM, she is not going to care one iota how YOU feel and will be glad that this is bothering you.

Your husband needs to take care of this. I know for a fact that my DH would not even go to his sister's wedding if she invited BM.

Lack of boundaries all around and your H needs to stop being so passive and start regulating sh!t NOW. There's no way she should be in any of your functions and if the Inlaws invite her you're going to have to create boundaries around that also. She may still want her Ex back but its up to your H to make it clear there is no way that's going to happen. He has to leave no room for assumptions and perhaps the fact that she's so involved in all these family functions makes her think she has a chance. 

Whatever you do don't contact her as this is your H's situation to deal with and if he wants a happy marriage he needs to act accordingly.

"I have talked to my DH many times about that, but he says I am overreacting, and honestly seems to be protecting her"  This sounds like a game.  His ego swells every time he feels there are two women after him.  Do you have any contact with an old boyfriend or possibly a nice man at work?  If you don't make one up, and start having some fun yourself.  I'll bet you DH won't like it very much at all.  Tell him you will stop communicating with your 'admirer' when he tells BM to stay home.

Both BM and your DH have displayed gross negligence in boundaries and boundary breaking. Is his ego that fragile he needs the strokes (men who have been cheated on always seem to need bolstering.)

You should tell your DH that BM is absolutely NOT NOW and NOT EVER invited to your events in your home, on your boat, in your airplane, in your shoe box, in your bathroom, backyard, pool - no where. Period.

How exactly does she "invite herself", unless someone is even mentioning it to her? How is DH's family even allowing this? SHE cheated SHE blew up the family. This tells me something is VERY wrong.

But first, your husband is gaslighting you and invalidating your feelings. Get him on track. YOu might have to "over react" a bit more, because making you uncomfortable should make him uncomfortable, yet he seems to actually be perpetuating this.

Make him understand that he has to choose, he cannot date both of you.

And no, absolutely do not say a word to this BM.

I would lose my $hit if the ex ever showed up to one of our events. Similar to you- she was trying to get him back for years. I'm younger. blah blah blah. I agree that DH needs to put an end to this immediately- soooooo disrespectful to you.

Here is the "riot act" I would be reading your husband, if I were you.

You know, I think I have been very mature and tolerant of the fact that your EX has been included in so many of our events.  I mean, I get that there will be events that your children have that both you and your EX will need to be in the same place.  Funerals, weddings and graduation events come to mind.  But this endless parade of inclusions for drinks, holidays, boat trips?  I really was being nice by not making a big deal about it.

BUT.. your Exwife has crossed a line and I am no longer inclined to play nice with someone that has made it clear that she still has feelings for you and wants to break us up so she can have you.  So, going forward, she is not welcome in our home.. for ANY reason.  She can have her own holiday and birthday celebrations with the kids.. and you have a separate one.  The only functions I will attend with her present are those where it is a public forum.. such as a sports event for one of your kids or a graduation ceremony.  An exception for the time when your joint kids will be married too.  But that's it.  I am not going to parties at her place.  If your relatives insist on inviting her to their celebrations?  I will likely choose to decline.  She is your EX wife for a reason.  your family should show their loyalty you and your wife (ME) by not fraternizing with a woman who cheated on you and broke up your marriage.  I am done playing nice.  If she invites herself to our home, you will find me marching her A$$ out the door.. so I advise you to figure out how to make that not happen so your kids don't get to see her humiliated.  I am done being the doormat.  I am done playing nice with a woman who is angling to steal my husband.  I am not going to sit back and let her make a play for you in my own home.  If I find that you are going behind my back to allow her here, I'm going to consider that a betrayal of my trust in you and a betrayal of our partnership in marriage.  If you are going to make someone pissed at you.. I strongly suggest you decide for it to be her.

Esmod's riot act sounds good to me!

In your shoes, I would not talk to her - there's no need.  You need to talk to your husband.  HE is the problem here.  He is the one that for years has failed to put up boundaries and show respect for your position as his wife.  When he tells you it's not a big deal or you're overreacting, etc., he's gaslighting you.  He needs to be read the riot act.

An X has no place in their X's family. Period.  Ever. For any reason.

My XILs used to invite me and my family (DW & SS) to their home and to family events and celebrations. I always politely declined.  I didn't have any interest of ever laying eyes of their cavern crotched skank whore of a daughter ever again nor did I have any interest in exposing my family to them.

I have thought of what I would do if invited to a funeral of one of my XILs.  I think I would politely decline.   Though I was actually pretty close to my XMIL and XFIL while married to their skank of a daughter.  Over the years I learned far more about them than I cared to know.  But their legal troubles did end up putting my XMIL in federal prison and they lost a lawsuit by XMIls past employer to recover the $Millions she and her family embezzled from his business.

Your DH needs to hear the "her or me" message .... and firmly.

No more can you tolerate BM in your life.  And neither should your DH nor should his family.

Throw him back and take him for everything.

They all deserve each other.

Hate to say this...but he’s afraid to totally let her go. A part of him is still in love with her, outside of her being the mother of his children.

Hes keeping that door slightly cracked...juuusssttt in case he needs to get back into that relationship. He can say there’s no way in h3ll as much as he wants, but his actions show otherwise.

ESMOD said it perfectly-this needs to be corrected immediately. 

BM recently tried this crap.  I refused to attend any and all events she attends, and DH called me "insecure".  Probably because he'd be lonely, and when we go BM usually has some utterly dumb/crazy/awkward conversation, my favorite was when her now ex-h was trying to get very fat to gain disability (didn't work), and we usually have a good laugh for a month or two.   Anyway,  I explained that if I were truly insecure, I would be hanging all over him, showing up BM.  I know I don't need to do that, and if he ever made me feel like I had to do that, I would just let her have him.  No man is worth that kind of stress.  So, DH eventually called her creepy to her face, and it stopped.  He's also refused all invitations except the one, without even asking or telling me about it.  Smart man.

How many years have you been married to him?

OP, never mind. I went back and read your post about your husband wanting to build/buy a house with his MOM?

I am sorry---so your newly married.

I'm Catholic and if you are, you should be able to get this farce of a marriage annulled. A marriage is between 2 adults, not mommy and his ex.

It's your home.  BM would never step foot in it. Not attend a party in your home.  DH can't have his cake and you.  This would be a big issue for me.  
When I first got together with DW. She brought the kids to the EX so he could see them and she stayed there wity them and the ex. ( for the kids) ( and I was paying for her gas to the ex)   She said she went to the neighbors, I did not believe that story.  Told her if she did that again I would leave her. And I meant it.  No playing Happy Family with the ex.  It she wants to play with the ex. She could have him.  Not going to be a threesome 

The man has a girlfriend.  That his girlfriend is also his ex-wife doesn't suddenly make it okay or mean you have to accept it.  Or any other nonsensical pitch you're being given.

You'd not tolerate your husband having his needs met by any other third party so what makes this woman different? What makes her so special as to overlook the complete disrespect your husband teams up with her to dish out not only to your relationship but you personally?

Their joint almost grown arse kids? Ha!  

Love yourself the way you wish this sorry excuse for a man would.  You deserve so much better than what he's offering.

Your husband disgusts me. He is treating you like crap by allowing BM to come to these events and by entertaining having these conversations with her. She is way to present in his life. This is not her this is him he is allowing it because he likes the attention and he likes hearing that this woman still loves him. It strokes his ego and it keeps you insecure which I'm sure helps him get what he wants from you. by keeping his current wife on her toes she's going to be extra obedient and try to please him, am I right? He's enjoying having you to fight for his affections. I hate to even mention this but I really do wonder when the last time they had sex was because it sure as hell has been less than 10 years ago when they first split.

I'd love to see the look on your H's face if you had an X constantly come around and you treat it like "its no big deal" and he should just suck it up. I mean really....what the h@ck is wrong with this man and the entire family?!?

No way you can continue letting this continue OP. You either stand up for yourself NOW or accept that this will be your life. 

Maybe he needs a therapist to explain how inappropriate this is to him? Would he go to couples therapy with you?

I could also see the option of trying to humilliate him and his ex in front of everyone, if you think you could pull it off. A well timed comment in a group setting where you laugh about her trying to get back with your husband could stop this nonsense. It could also just blow everything up and make it all worse and make you seem insecure...so it is a risky move. 

Another option is to get his family on your side so that they stop inviting her and stop tolerating it when she crashes celebrations. 

Here's a gem I learned from a good therapist. Anyone who is not a friend of our marriage cannot be a friend to either person in the marriage. Period.

BM has made her intentions perfectly clear, and she is no friend of your marriage! Your DH needs to make HIS intentions perfectly clear and protect his marriage to you. By doing nothing he is subtly encouraging her creepy behavior and in the process you are losing faith and trust in your husband. That's no way to live. .

This would be a hill to die on for me.

We never lived nearer than 1200 miles from the SpermIdiot.  So, his pathetic efforts to reconcile with my DW were through manipulation of the Skid.

For a number of years early in our marriage SS would come home form spermLand with the SpermIdiot's shit and ask "Mom, DaddyDickhead wants to know if you still love him."  She would tell SS that she was married to me and that DickHead needs to stop asking SS those questions. (We never referred to him as DickHead.)

DickHead did call a number of times over the years crying about how he loved her and missed his family, whaaaaaaaaaaa! No mention of the three younger spawn and other two baby mamas of course.

DW would laugh at him then ask him is he wanted to speak to his son.

When he was 22 SS-27 asked me to adopt him. We made that happen.  DW, SS and I visited SpermLand to spend time with my ILs last year (2019) and SS spent an afternoon with SpermGrandHag and his three younger also out of wedlock SpermIdiot spawned half sibs.   She called the Spermdiot to come over and his answer was "Why would I want to do that?".  So SpermGrandHag handed SS the phone.  He answered DickHead's question by sayin "Because I am only here for a few hours you asshole!".  So the SpermIdiot came over.   After they hung up the phone SpermGrandHag told SS she was glad that he had grown up with a father who loved him and was a good example.

For the last half of his growing up whenever DickHead would go into his "I still love your mom sooooo much, does she still love me?" crap SS would laugh in his face, tell him to knock it off, that his mom was happily married and that she loved his dad very much.  Of course, "Dad" was, is and always will be.....  me.