What do I do now?

I just cut myself for the first time yesterday. It made me feel so much better, but now I'm scared. I didn't mean to do it, it just kinda happened. What do I do now? I never thought i'd do something like this, but once I started, it was hard to stop. What does this mean, I'm afraid that I won't be able to stop now. I just wanted to talk to some people who know what I'm talking about. I don't think my friends would get it. Thanks
Meg