Like you, I'm planning to ask AH to leave. My backup plan was to stay with family for a few days while finding an apartment if AH refuses to leave. I tentatively broached the subject of asking AH to leave with my family (did not even mention staying with them.) They were all clear. They believe my DS is being a brat and needs to "compromise" by coming home and I need to suck it up and stay with AH. When I mentioned that AH was not "compromising" or working to improve the situation and used concrete examples, they said that was just my perception? Not sure how AH not going to AA, quitting counseling, not making any effort to contact DS, and starting drinking again is a "perception"? End result is that I'm now working on a backup plan that does not require me to rely on someone else or stay with family.
I can understand how difficult this must be. I was thinking of bringing up the subject with my mother about the fact that I am considering leaving my AH, but after watching her fawn all over him an tell everyone at the table how wonderful he is during Christmas dinner, I don't see that happening at all. These two could not stand one another a year ago, and now they are buddies. Of course, I have suspected her of NPD for several years, and everything that happens in her life (and those around her) must be at her convenience. So, no family support here either. My back-up plans will involve my friends instead.