M.G.
I teach 8th graders, am a youth leader in our church and have gotten very close to a lot of my kids. This is such a common thing. It's completely psychological. It's not that they like hurting themselves. They do it for several reasons depending on the person: *it's a control issue much like an eating disorder, and it's the only thing they feel they can control themselves *when they are hurt by someone or angry, they haven't really learned what to do with those feelings. They feel a relief from that hurt, pain, stress, anger by cutting *very rarely do they do it for attention purposes, but it still is a slight possibility.
You need to just be there for him. Talk to him every day and not always about cutting. Talk to him about his feelings and help him understand them and how to handle them. If you see him get angry or upset, etc, be with him! He needs someone to help him figure out how to handle his feelings because that is the most common reason for doing this.
Don't even talk to him about the cutting unless you can tell he's wanting to talk about it. You'll get to where you can figure that out. You can also eventually find ways to get him to talk about it without you ever even bringing it up. Pay attention to what you do when you have those types of feelings and let him see your reactions (which means you really do need to pay attention to what you do).
It's a very sensitive issue, but he needs help from those close to him. Be a friend to him so he will come to you and talk to you about his feelings more. More than likely he has friends who do this too, so they are the influence he sees on how to react to the feelings he has. He needs someone more positive who knows how to handle the feelings. Don't bottle yours up. Show him how you really react when you get frustrated at mom or stressed about school or work. People handle things differently. Some journal, some listen to music really loud, some run, some scream (if you do that, you may want to make sure you aren't screaming AT someone :o). Be positive, and the most important thing you can do is love him through it all. Good luck.