The fear is that setting a boundary will drive her away when the reality is that it will attract her.
Absolutely true in my case. Everything that she says is counter to this. "You don't trust me, how could you think that, I would never do something like that......" So I start doubting myself. With doubt comes inaction. I should have been in action mode for months. I have no reason to trust her at this time and she knows it. Hopefully, it's not too late. I have dropped the rope and exposed to certain people. Time to continue the hard work.
And if it doesn't work? I'm at peace with that. Other than still worrying about the kids. Can't quite get over that stumbling block. D would devastate them. That will be on her.
