I use to cut but don't anymore. it takes time to find other ways to cope with things. Do you know what triggered her? may be you should try and take away the sharps and dangerous objects if you are self-injuring. however you can always by more. what was the consequence for self harming? Is there any positive reinforcement you can do for her for not si.
I found selfharm does not get you anywhere. No one really cares beause you are only hurting yourself physically. Emotionally it sounds like your hurting your bf. How is he copeing with all this? That is alot for someoen to deal with to see someoen they care about hurt themselves.