When you're dealing with that kind of insanity sometimes all you can do is disengage to a degree.

Let go. Don't feed into the sickness. They will lead you around in circles if you try and do the normal adult thing of talking it out, working it out.

If there's much projection and blaming it will only drive you crazy if you try to reason with him.

Quit playing the game. I'm not saying you are playing games-he is.

Renew old friendships and hobbies.

Leave the room when the shit gets too deep. If it's really like that you don't owe him an explanation.

Do something for you and let him sputter off by himself.

We went thru all of this in our early years...

DH took me out to dinner for my birthday, then announced that the Ex used to work there (I guess that's where he met her?) I picked up my napkin, placed it on the plate, and walked out. That is just one of the many things he did, I'm pretty sure he wasn't being malicious but all I could think was WTFE??!!??

And he would have convo's with BM and get angry, then for the next 3-4hrs anything I did was W.R.O.N.G... I would point out every single time that his anger was misdirected and it needed to stop. He wouldn't listen

So when he would get in his moods, I'd say, Guess you've been talking to BM." and then I'd walk away and remove myself from the argument, giving him time to consider his behaviors.

For a while he was seemingly always at her beck and call, if she needed help with something she'd call him and he'd do it. But he used the excuse that I'm an able-bodied, independent woman and I didn't need his help, that's why he rarely offered. So every time she'd call needing help, I'd come up with something I needed help with, and my requests were always just as small and meaningless as her requests... to the point they became annoying to him. He finally made the comment one day that he was sooooo busy doing everyone else's bidding that he didn't have time for himself. That's when I went in for the kill and pointed out that his priorities should be RIGHT HERE, and if he would stop letting her run him ragged, he'd have a LOT more time. ~OR~ if she would start asking HER HUSBAND to help her out, she wouldn't have to call my DH. And no, most of the stuff she called him about had NOTHING to do with his kids.

I tried rationalizing, I tried talking, I tried all sorts of different things. But then I decided to fight fire with fire and eventually it worked.

I think he had allowed her to run his life even after the divorce (they were divorced 7+ years before I came on-scene) and always rationalized it as having an obligation to her because of the kids. I told him if he continued to feel he was obligated to her on such a deep level, he certainly didn't need me in his life taking up valuable time he could be using for her, and if his priorities were going to lean towards her, I had no place in their relationship.