Tread it seems your W has moments of showing nice moments but continues to openly engage in at least the A with OM.
I think a physical separation might help your sitch. It seems with the last thing you mentioned W likes to pretend there is a happy family. Obviously don't neglect your child but maybe it will help her get out of her fog if she 'loses' being under the same roof.
This isn't easy. Like I always say: follow your gut. But I wouldn't be able to remain calm and focused if my W was openly interacting with OM and making it seem to me that it wouldn't be a big deal (that is what I think you are saying is happing with her).
If you don't do a physical separation maybe not being physically available might also work. So she might see you late at night or early morning but she doesn't get to do things with you.
I am sorry you are dealing with this. There doesn't seem to be an easy or straightforward step for you to take.
