Just because you slipped up doesn't mean you should give up. You have an admirable goal in trying to stop self harming. Having a slip up doesn't change that. I can understand the mixed emotions. On one hand you have a sense of relief and are able to let go of some painful emotions. On the other there is shame and disappointment that you hurt yourself. Try to dust yourself off and try again. Everyday you can hold off the urges and treat yourself good is a victory.