I'm about 7 months pregnant now, so I can't answer all your questions, but I can keep you updated!
I have a wonderful husband and another guy I'm seeing, Sven, with whom I have a relationship best described as a warm friends-with-benefits arrangement.
I have maintained sexual and emotional relationships with both men through my pregnancy. I do wonder what will happen when the baby is born in 7 weeks (give or take!). Many women lose the desire for sex from sheer exhaustion for a few months. I sort of suspect, though, that I might be the sort of woman who will want to re-establish intimacy in some way with my husband pretty early on, even if I can't manage vaginal intercourse because of tearing, etc. But... we'll see!
What will happen with Sven is up in the air. We've had a thing going for awhile, and I'll be pretty heartbroken if he just sort of... drops me because I have a child. I hope that he will still be my good friend at least. I know that I will have less time to pursue Sven in the same way I do now, and that, because of that, our sexual relationship will probably fall by the wayside. He has a roommate that doesn't know about us, making encounters hard to plan already, and having a child will add an extra complication...
We don't have the kind of relationship where he would be expected to co-parent. But I have this fantasy that he will visit me and my baby in the hospital. I don't know if he'll even be in town. I'm giving birth over Christmas, and he has out-of-town family.
Anyway, we'll see. I guess the short answer is that I don't know what will happen with outside relationships when the kid arrives, but that I know two things: a) that I will have less time for them, and b) that I probably won't want them to completely end.