Poor kids, they are often the ones that end up kicked to the curb and falling through the cracks!
I admire your BF for taking an active interest in his daughters well-being instead of just saying to hell with it.
It does put you in a quandary, though ...
Who knows, once the daughter is here and out of the reach of her mother's influence she may exhibit a whole other kind of behavior!
Wishing the best for all of you!