It's really tough with kids. They slowly kill you with their problems, and we feel we deserved it somehow.
I'm still learning how to set boundaries with my kids.
I don[t know what you should do as you are the one that's going through this pain with your daughter.
If you can find some way to show her how to be tough (internally) and teach her to overcome her inner demons, eventually she'll grasp it on her own. Hopefully.
Best wishes.