At the end of the day you're turning to this coping mechanism for a good reason - so there's no use chastising yourself with guilt. The problem with self harm is that it provides only short term relief - so instead of focusing on the shame and repulsion surrounding this activity, focus on it's pure ineffectiveness. I think the more neutrally we look at an issue, the easier it is to find an adequate solution. Self harm is usually symptomatic of something greater - what is it in your life that needs changing? Can you identify what sort of help you might need in order to make said changes?

I think we need to stop looking at self harm like some terrible, purely ominous event from which there's no return. It's merely an indicator that something has gone wrong and that now we need to use it to spur ourselves onto better things. It's not really the act but more the outcome that needs our focus. All the best to you.