I discovered self harming when I was ten. I did it off and on through my adulthood.

I was able to stop about twenty years ago: my PrevT (whom I adore) told me that if I did not stop she would not see me any more. I had to decide which I wanted more- PrevT or harming.
I don't think I did it perfectly but I stopped harming.

Looking back, I don't know if PrevT was bluffing. I don't think so. It was manipulative of her, for sure.

I think I coped by leaving many, many voicemails for her describing different hurts and anxieties that I was having...instead of self harming. (This was before I had a computer or email privleges with her.)

A year or so later I tried self harming again..but it didn't do the same thing for me anymore.

I hope this helps you.