URGWNT!!!!!!!!!!!!!!!!!!!!!!!!… i need to stop my girlfriend from cutting. HOW????????

god, i feel as though i am another helpless teen. but i am running out of options. my girlfriend is a cutter due to her moms constant arguing. sience we have been dating, three months, i have tried to get her to stop. she wants to but doesnt. she has no other ways to cope with her emotions. she last her razor at one point. she got another one about a week and a half later. she had a break down and gave it to me because she "doesnt wnat to lose me" and during that time when she did not have anything to cut she went through withdraw and attempted to break up several times. she was almost pver then she found a pocket knife. so she started cutting again. i have been talking to her about it and told her it has starting to irritate me. she is giving me the pocket knife but she is really mad at me about it. she surfers from depression and being bipolar. i have put up with the last of it. i have run out of options. we need desperate help...