What is the psychology of people who abuse themselves when they are angry?

Self-mutilation is a kind of revenge for yourself. You can't vent your temper, you must release it. In fact, when you are angry with others, you will also feel disgusted with losing your temper. After a long time, you will be dissatisfied with yourself, so hurting yourself, to some extent, is your own inner suggestion, but also hurt, which will divert your attention from angry things. It will be more comfortable. So the so-called comfort is just a relief from another kind of pain.