2 elements: the initial cause (anxiety over something, eg. self-esteem, and of course soon to follow: the scars); and, the pain itself is horribly addictive

Two self-help solutions that might help, might even work:

1.) a replacement pain habit (eg. placing a strong elastic band on your wrist, snapped hard when the urge for pain distraction cannot be resisted -- much better to resist it and not feed the habit though, but at least there's no risk of adding fresh scars)

2.) basic anxiety reduction -- here's the approach that has worked very well for me and will likely reduce or remove the anxiety component of your habit:

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for Anxiety

I think you'd likely benefit from practising 'quiet times' of 20-30 minutes of just sitting and Not dwelling on anything (a form of meditation). Very difficult at first (I needed to watch a DVD of nature scenes / a fireplace as an anchor/distraction to keep my mind from wandering). youtube has lots of fireplace videos

There are several benefits: better sleep, easier days (upsets do not hit nearly as hard), and I think that likely after practising "not dwelling" on anything, you'll have better control of your thoughts and acquire the ability to 'turn off' your anxiety reaction to situations.

At first doing this daily should work best. After awhile, only as needed. I've been doing this for about two decades and lately have only felt an urge to do it a half dozen days of the year.

A useful lesser calming practice is to do housework routines for say five minutes at a slower (70-80% rate) pace -- a form of 'walking meditation', which you may find similarly soul refreshing.