As hard is it to think clearly through all these dramatic phone calls and outside pressure from her family to do x,y,z, let's break this down to one simple question:
What's best for the children?
A short stint in rehab does not a recovery make. The children will. not. benefit. from being cared for, or in the presence of, an alcoholic mother whose judgment is cannot be trusted at the moment.
Your account of her family makes me think that they are still caught in the enabling loop. They are attempting to lay the blame on someone (or themselves, for not being "supportive enough") or some event (such as "abuse", for causing all this to happen)...and by doing this, they are *robbing* her from the opportunity to find her bottom HERSELF.
(and as a side note, I was raped by my physiotherapist as a teenager, and I do not use the experience as a justification for ...anything).
Now that you have told your AW the news about her not coming home, I would limit your conversation to the bare necessities. No, she doesn't get to choose the nanny. Yes, she can talk to the kids. That's it, that's all.
Focus on yourself and your kids. If you can't make it to Al-Anon, like I couldn't when my DD was still nursing, try an online meeting. It's not the same, but it's at least something.
Keep posting!!!