My husband's family is toxic as hell and we went through a similar thing a few years back when he was, I don't know, finding himself or something. I knew what was going to happen if he reached out to his mother.

That said, I have a kinda loose rule, his people, his call, my people, my call. I told him exactly what I thought and how I felt. I also made it clear to him that he was free to rekindle any relationship he wanted with HIS people, but I was also free to not be a part of it (unless and until I saw a marked change in said people - spoiler alert, I ddin't).

When he was disappointed and hurt, yeat again, I was there to pick up the pieces and that was the end of that.

I feel for you because it's so hard. It's like watching a train wreck and not being able to prevent it. You know exactly how it's going to turn out and there's nothing you can do about it. There's very few things worse than not being able to protect someone you love, but maybe he needs to do this to close the door on her once and for all. Just my thoughts, for what they're worth.