Hi,
I'm so sorry to hear you have started to self harm. And I'm not going to say you should stop here and now and never do it, I know it's not that easy. But what I will say is try hard to stop, and talk, talk to people. Distract yourself as others have said, and try a negative image technique I suggested to my friend. When you have the urge place a negative image in your mind, something self harm might lead to then stop and think do I want that. And you mentioned you wanted controll of the situation, doing this stopping to think, do I want this? And take controll and put what ever you have down and walk away.
And we're all here to talk