Hi,
I'm sorry you are going through this. That's awful! Those parents sound terrible! I think the only thing you can do now is let your daughter make her own mistakes. She probably will realize hopefully how bad it's been for you and try and change the situation. My son hasn't contacted me in 30 years and I'm not really sure why. All we can do is pray for them and hope we raised them right so they eventually realize their mistakes.
I wish you the best.
PML