Ditto Lexie.
We are so rooted and raised in not making other people uncomfortable that we can continue violating our own sense of safety and self even after we are no longer hostages of an A.
I would not buy him tickets. I sure as hell would not sit with him. But I've been divorced for a while already - I care less what people might think, and the kids are under no illusion that we are a happy family.
Don't beat yourself up over it - but remember, you have zero responsibility for doing ANYTHING for him.