Getting help is very important. If that is not an option, just talk to a close friend. There are also many things to do instead of self-harm. Some people recommend distraction. I personally think putting ice cubes in my hands would work better, as this hurts, but it doesn't do any real damage (Note: this is an in between step and probably not healthy as a long-term solution). Also, don't carry around SI instruments with you. This means if you suddenly get the urge to SI, you'll have a harder time finding something to do it with and this pause could be enough for you to think, maybe I shouldn't do this right now. I wish you the best of luck and hope your problems get easier.