What if you changed the line "It would have been a great life if his exwife..." to "It would have been a great life if my HUSBAND...".

From what I read, obviously the BM in your situation has a lot of problems. But the truth is you can't change her. But your husband doesn't sound like he's your partner in all of this. If he's not valuing your opinion, how does that make you feel? How do you define a partnership? Do you believe that both you and your husband live up to the "partnership" you envision?

Have you and your husband ever participated in counseling?