i cant relate to this friend of yours, i cut myself because of my dads illness because i feel as if its my fault he is ill and i constanly argue with my mum. i have took it upon myself to try and get help i thought it worked at first but then i did it again, i found that all i need is my friends to be there for me and keep me happy so that i dont let my mind think about things that will bring me down, just try and be as supportive as possible and make sure your friend gets rid of her boyfriend,, he's not making her any better
1. get rid of the boyfriend, it might not be easy but you copuld let her stay with your family for a while so he won't give her any trouble.
2. Help her to get close to her other parent, they could help each other because every one knows this is a difficult time for anyone.
3. Get someone you know who goes to her school (cousin, nephew ect.) to keep an eye on her and stop anyone giving her a hard time.
This is all i could come up with so i hope it helps.