Abuse is THE most awful thing that could happen in a relationship.
I've been mentally and emotionally abused by my ex for over a year and a half (we're both bi but in a straight relationship). Everybody knew it was wrong, even I knew it was wrong and I still loved him. Even now I sometimes tend to make excuses for his behavior in the past. He left me when I most needed him because my miscarriage was my fault and he didn't love me anymore. He even made my life even more of a hell af6er he broke up with me.
1,5 year after it happened I can look back on it and say that I'm glad my family and friends were there to catch me when i fell.
Rush, I can only hope for your daughter that her gf breaks up with her. She is so caught up in everything that she can't leave. I hope she will be able to pull through. Damn, I don't know how to say this, but hopefully she will fine someone that can safe her.