There isn't one normal way that people react. Usually there is some shock - it isn't an easy thing for someone to come to terms with. If it's someone close to you, quite often they tend to question what blame they might have in you needing to hurt yourself, and sometimes they can't handle that thought at all so they deny that it's true at all, or invent some explanation that they can deal with more easily. Other confidantes will also have their own emotional reaction to deal with, and disbelief is probably fairly common. There is more awareness of SI these days than there used to be, but I think people still think it is very rare (actually about one in a hundred people do it, so chances are most people know someone who self-injures), and we tend to be pretty secretive about it. When I have told people, the main reaction has been curiosity, and usually concern. Some did want to see it, because they were just curious about it, and had a lot of questions. My husband thinks that I do it to hurt him, and does tend to take it personally and feel hurt. There have been three therapists that I have told - the first didn't seem to believe me, and I didn't think he even heard me until he confronted me weeks later. That one was over 15 years ago. The other two have been very accepting, acknowleging that there was a reason why I hurt myself, and they didn't focus on the SI, but on the other things that I needed to work on. Hurting yourself is a symptom that there is something you need help with - it's not the real problem itself.

Next time you talk to your friend, you might not even talk about SI at all. But you could be prepared to give him some basic information about it, and if you are comfortable you might explain why you do it and how you feel that it helps you. Maybe also you could discuss what you are going to do about it - if you are harming yourself, there is something wrong and it really takes a professional to help you to work through it. If your friend feels like he needs to be responsible for helping you recover, that is a pretty big burden. I'm not saying that you are expecting that of him, but he may feel like he does need to do something to help you. He can't take on the responsibility to be your therapist, and needs to know that you don't expect him to, although if he is willing, he might be a great support to you in getting professional help (if you are not already) and providing social support as you deal with your issues in therapy.