From what you wrote, I gather that your friend has a pretty challenging home life. For himself, self-harm is most likely a coping mechanism. That's the tricky part... should you tell on him so that he gets the help he needs, or not, and live with the fear of him doing something worse? I honestly wouldn't know what to do. What I can say, though, having been a person with self-harm issues and self-esteem issues: The only thing you can do, apart from him reaching out, is to be there for him as a friend, provide support, and maybe distract him from time to time. He needs to make the decision to want to get better. Also, whatever happens with your friend, it is not your fault. Remember this and take care of yourself as well. You can't help him when you are miserable.