So are you saying because of my mistakes I should endure that? If so, is it fair to me, really? Is it fair to Ds? How long do I do it? What are the appropriate terms? Do I concede custody and give up time with the girls because their other environment is better?
No, I am saying that you need to recognize that you have set a precedent based on an expectation that she might come back to you. Expect her to feel bombed again and just do what you have to do.
It just sucks but it is what it is.
Figure out (perhaps with an outside person...IC, D's C, L etc) what is in the kids' best interest.