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.
MrP is right on here. This is the recipe I use and trust me, while it may seem difficult at first, if you do this regularly, you will feel better about yourself and less concerned about her. I am at the point where, when I see her and minimally interact with her, I think, "Hmmmm, I used to have a history with someone who looked sort of like this person here..."
Me 59 W 47 T 26 M 23 S18, S14 BD May 2023 D filed June 2023 OM1 confirmed: December 2023 OM2 confirmed: October 2023