My friend cuts herself and i dont know why?

i just found out yesterday that my friend was cutting herself. My buddies cousin texted me yesterday and said that my buddy was cutting herself. Words cannot explain how i felt when i was told this. It made me fill up with rage and i was already pissed at that moment and finding this out made it worse. I started to cry because jus the thought of her cutting herself is painful not only to her but for me to. I mean a couple of my other friends did it and my reaction was the same. I cant stand it when my closest friends do that. Now just typing and thinking about it im starting to cry dammit. Pero anyways, i dont know what to do. On myspace, her status says im worried as **** and a sad face and i asked her watcha worried about anjd she said i cant tell you and that pisses me off, especially when i had a feeling something bad was going to happen and it had to be her cutting her ******** self. I cant take it anymore i dont even know what to do and i tell her im here for you if you need anythin bbecause shes here for me just like she says and i apperciate her for that but this is killing me literally, like everytime i think about this, ifeel like i cant breath, i just care about her to much for her to be in pain, [lease help me and dont leave any mean comments cause thats the last thing i need in a time like this, thank you