Someone once asked me why I hurt myself, and I answered: because it works. And it does. Temporarily, yes, but when you are suffering, a brief respite of any kind is welcome. Once you know that, you can't UNknow it, which is what makes it so hard to resist using it as a way to help yourself feel better again. Injuring yourself forces your brain to release endorphins, so you do literally feel better for a short period of time. Injuring yourself can also trigger your survival instinct, which can be enough to ward off a suicidal urge. So on a chemical level, its a perfectly reasonable thing to do.
It just also has longer term negative effects. (Which I know you know well) for me it just helps me a little bit to know its not a totally irrational thing to do. I really hope you will continue to feel better. It sounds like you're working hard.