Sweet lil' sis !!
You expressed perfectly what I had felt more than once...
I have cut myself, hurt myself, tried to kill myself sometimes, because I wanted "that guy" to notice me, to gain his attention... Like "oh, she is in the hospital, poor majo !!"
And some other times, like you said, to make him feel guilty and also, to make him realize what he had lost...
The worring thing is, that sometimes hurting me makes me feel better

even when that guy of course, simply continued his life...
How sad is that ?