With a razor? Yikes. Having a loved one who inflicts extreme self-harm upon him/her self can be severely traumatizing. My great-niece I am haunted by what she did to herself and obsessively think about her every day.

I think it's kind that you are supportive of your friend. I also believe that it's important to make sure he remains as just a friend. Take good care of yourself...which might mean setting boundaries on the energy you give to him.