Joining Gagrl in welcoming you
Being on the sidelines is
so hard. What kinds of demands is he giving into?
He's caught in a tough place but giving into her demands only emboldens her (you probably see that ...). To him, he probably thinks "I can deal with this issue and it will die down, then I can rest up until the next time it happens" not realizing that more effort spent upfront is better if the goal is to dial down the long term nuttery.
Do you have boundaries or limits that you've communicated to him? How do you frame them and how does he respond?
I had to stop focusing on what my H was doing/not doing and start figuring out what I had actual control over, and then work from there. The hardest part was allowing there to be tension between us, but it got easier to see that these dust-ups were kind of necessary (and temporary). In our relationship, it's more his daughter (23) that I have issues with, but his ex is also BPD. The age of the kids makes it a little easier when it comes to dealing with her.
What happens when you disagree with your partner's actions when it comes to BPDx?