I'm not a vet but I read up on your situation. Your W sounds very similar to mine in a lot of ways, as does your situation when the first bomb was dropped many years ago here.
What I did back then (eventually) was to calmly and simply tell her I had no intention of leaving my bedroom, my house, my kids, or my life because I had not done anything to warrant that. If she wanted to sleep elsewhere or move out it was her business.
I didn't do it in an angry or confrontational way...just matter of factly.
However, if she starts trying to lock you out, etc., I'm not sure how best to handle that. The important thing is not to create a traumatic environment for the kids. If she moves your stuff out when you're gone, etc., you may need to just go in the extra room.
The thing I noticed while reading your sitch, though, is that I don't think you're detached...believe me, I have always had a hard time with it too so I feel for you. But I would avoid going much out of your way to accept the "little nice things" like donuts that she tries to do for you occasionally until there are definite actions on her part that demonstrate she's establishing appropriate boundaries from OM.
If it were me I would regard them as attempts to manipulate, check your temp, etc. and therefore not helpful to you at all. I'm not saying don't accept...but don't go out of your way, don't get too excited about it, and don't use it as an excuse to think things are different.
