This may or may not be a good idea. You do want to show her love and support and it's really difficult becasue cutting and an eating disorder such incredibly secret destructive things, so when someone confides in you there really allowing them selves to be pretty open and vunerable. Speaking from someone who has had an e.D, sadly there isn't much you can do, if she wants help she'll ask for it, until then she will deny it, so in that matter its her move. The cutting- my advice would be, offer to go to a counselor with her and show your support in that matter. That way she can atleast feel a little more confident about getting help. I also would want to say tell one of her family members- mom - dad, but that would most likely make her back off from any help you could have been close to getting her. It's kind of a coin toss, but your being a great friend just by bbeing there, so goodluck!!!!!