The way i see it is you have 3 choices, walk away and see your kids as much as she allows and living as close to them as possible, move further away and risk losing contact or seing them infrequently, or go to court for shared custody or full custody. If it goes to court you will probably need to stoop lower than a snakes belly with any ammunition you have to get any kind of result,which i would’nt have a problem with if it was best for the kids.
I have no idea what the longterm outcome of any of these choices would be though.