I just want to enthusiastically second what Bustorama says above. When someone violates a boundary, and depending on how severe the violation is, you have to take some kind of action along the lines of the progressive boundary list (which is great). All you can control is you AND it needs to be something substantial. To me, you don't sound like you're ready to D and, if that is accurate, then perhaps you're at a point where you engage in minimal discussion (only about kids and household administrative priorities). I'm also dealing with detaching while under the same roof. I treat W like an acquaintance at this point: minimal conversation not initiated by me, minimal details shared about myself and what I'm up to, often in another room doing something I enjoy, getting out and about when possible. I expect that can be tough when she continues to put you on the hook for caring for your kids. As a child of divorced parents, I can tell you that even young kids will remember which parent was there for them so make the most of the time while you can.
And, tell your W with some advance notice that you need to go out for a bit and ask that she be home for them. Don't make it a negotiation. Or, get a sitter or family member if need be so that she can't argue you're trying to control her by making her watch her own children. Ridiculous? Yes. But, this is why you'll sometimes here people refer to spouses behaving in these ways as having been taken over by aliens.
It stinks and I feel for you. I re-read the detachment and boundaries threads quite a bit, trying to continuously get better at both. If you haven't, I encourage you to spend some time there and toss out ideas for us to react to if that helps. We're here to help.
