Sometimes I feel guilty for self harming.
Why do you feel guilty about it?
I don't think that I'm justified in doing it.
You shouldn't feel guilty because of something that's wrong with your mental health, and you should instead seek out a therapist because you clearly seem to know this is wrong what you are doing which is the important first step. If you continue to self-harm then things could get a lot worse, and you could one day accidentally kill yourself.
I'm going to punish myself now. I deserve to harm myself.
Please don't harm yourself. You have no need to feel so guilty about it. I really want you to seek out some professional help though.