Similarly to Irele, even though I'm not a male, I've always been taught to in a way "be a man" and not let the bad emotions show through. And after doing that for so long when you mix in an emotionally abusing family; sexually, physically, and emotionally abusing boyfriend then it ultimately becomes too much to handle and the pain and stuff manifests itself in the only way you have been taught how...more pain. I'm not sure if this makes sense to you. I hope it does. But explains why I personally do it (although thankfully I have been clean for 4 months).
As for you doing it. I'm not trying to sound like a hypocrite, but it really it a terrible cycle and the day I regret the most in my life is the day I first cut myself. So please I know that when we do it we get caught up in emotion and aren't thinking rationally. If you get the urge (this is what I do now) try to use that little rational part of your brain to say no.
Best wishes! If you wanna talk feel free to message me any time
~SM~