I used to cut too, but couldn't hide the scars from others. I definitely didn't want people to see them, didn't want anyone to put me in a hospital so that whole "cry for help" bullshit is just bullshit to shame people in not doing it. Not a cry for help because Mom told him differently, may be a cascade of different things and so hard to hold it all in without lashing out at something or someone. But, I personally wouldn't want to harm others or my mom because I still have love for that person, so I think it's my fault in some way. Ashamed that I let someone cross my boundaries and didn't stick up for myself. Let them get to me, is a failure on my part so I take it out on me.
Just a perspective on that self-harm isn't always a "cry for help"