Spectacularly Insightful

WOW!  After reading the posts, I must agree with this insight, completely. 

Kids need stability, that's it.  And, sounds like your husband has always seen his daughter as someone else's responsibility. 

New custody arrangement would be prudent!  Doesn't mean that there's a "winner" or "loser" under such circumstances - for crissakes, it's the kid that should be the focus, not the adults!

And, I read one post that makes a very valid point:  you married this man KNOWING that his daughter had issues, and now you have the cheek to suggest that the child is destroying your marriage to this man?  I'd suggest looking a little further as per what the causes of this kid's behavior might be.  Then, I'd find a family counselor and get involved.

good luck