Does your school have a student health center, with counseling folks to talk with? If it does, go in however you can and talk with someone, they should be able to help lots and lots. I've done it myself when at college, in concern for a friend.

I think, and I easily could be wrong, what he is doing could go under the umbrella of self injury. There are some excellent resources both here in the Self Injury forum and elsewhere on this site.

Big hugs to you also for working so hard to be a good friend. There are answers out there, there is lots of excellent information and support available, there is hope.