OK..so you can't do anything until this child is born anyway, right? So divorce isnt' imminent at this moment.
Also, you don't have to compete with OM; but you can still listen to her when you're around and keep your PMA. Certainly with kids between the two of you, there are opportunities to show her what she'll be missing. But competing, no way.
You will definitely want to know her plans for this child after its birth. Is she going to have a custody/CS arrangement drawn up? My W wanted me to raise her kid as my own. I refused to lie to that innocent child; but it certainly would've made life easier for a while. Anyway, I bring that up because once you see that child and hold that child; you might think differently. But if OM is adamant about being in the kid's life; then you have already set your boundary. At that point, my best suggestion is that all communication about the child come through your phone and through you. No contact between W and OM.
It takes a really strong man to deal with this and if you've been dealing with a mental condition previously anyway? Well, you've weathered a lot already!!
