1) Go along with the bird-nesting (I think this is a no-go based on what you've said)
2) You move out and let her stay there (I think you know we all advise against this)
3) You stay and tell her if she really wants out that bad then she needs to make arrangements herself, that you are against breaking up the M but if that is her choice you will not try to stop her.
I think 3 is really the only option you're interested in, correct? If so then prepare for her to threaten to steal the kids again. If she does then you might disclose you have a lawyer and have discussed your parental rights with him and that he has informed you that she has no right to take the kids without your permission and if she attempts to you WILL take swift legal action. I think it may be time to let her know you're not messing around here. Edit to add- I would also stress you're not accepting anything less than 50-50 custody, I think you said you were OK with that? Put her on notice that you'll fight if she proposes anything less.
