I'm heading for the same sitch you're in and think the only thing to do is continue with the detachment/GAL plan - nothing is going to change where she is mentally anyway, and at least you can maintain your dignity and be a good father by sticking to DB principles.
I know how badly you'd like an idea that would "work" for you, but there just isn't a magic pill. Stay strong, stay patient, focus on anything but your sitch as as often as you can: it's those little mental breaks that keep you sane, help you sleep, remind you to eat, and allow you to see a future no matter what happens. BELIEVE ME, I know how hard it is. My situation is similar to yours, but she's planning to move into OM's house and take my son with her. Nice, huh? And there's not much I can do to prevent it.
