I think your friend is behaving completely inappropriately. Your feelings are totally understandable to me. I can't help but feeling suspicious of her motivation. My guess is that she has an appetite for weird drama. For any adult couple to want another adult to move in with them under these circumstances makes me think they're hungry for some kind of diversion in their boring lives. You might do well to quietly withdraw from contact with this friend. You don't have to call her and announce that. Just make yourself quite uninterested in conversation with her on any topic related to your divorce or ex-husband. She's making plans to orchestrate your ex's post-divorce social life?!! And she was eager to tell you that?!! No. That is not in any way normal or coming from a healthy mindset. Sounds like she is an attention seeker, likes to play with people's heads and wants to be the ring-leader of a farcical social situation. I don't have much respect for any intention your husband may have to move in with these two.

Shared childhood memories can be a powerful bond. Unfortunately, I think this is a friendship that may have run its course. I'ld encourage you to cultivate other friendships and not continue investing much in the connection you have with this gal. I'm sorry that, on top of the loss of your marriage, you also have to deal with such disappointing behavior on the part of a friend. You now have a double loss of two important relationships that have failed you. Maybe I'm drawing a big inference from a little information, but I suspect these are two people (the ex and the girlfriend) whom you may be better off not having in your future life. This is a time of pain for you, but little-by-little that will subside, and you will heal. And you will be free to pursue better, more authentic relationships. Cut this gal loose.