I need help helping a friend....

Today, I found out that one of my Friends cuts. She didn't tell me, I saw her wrist in English. I don't think she knows I know and I don't know if anyone else knows. My other friend will probably see this and make a big deal about it. I'm not saying it's not a big deal, but..... I don't know what to do. I don't know what to say to her. I want to tell her about the schmetterling Project, but I don't know how. I was thinking of leaving a note in her locker about it, but..... I've been holding it in all Tag and I'm scared. I'm scared one time she'll go too far and she end up in the hospital oder I'll come to school one Tag and find out she killed herself. She went to counsellor last Jahr when one of her ex-friend's told the school counsellor she cut, and she hated it so I don't want to do it to her again. Help?