How do I cleanse myself?

Over the past year and a half I have changed,grew, learned etc. But with all that and seeing the real parts of life I've never seen before and how people can be evil i actually became a rotten fruit too.

My way of solving problems is aggressive and assertive and I'm trying to change it. I've been going to therapy and I've already changed a lot for the better, but I still have that instinct to solve problems in aggressive approach.

(Not physically, but I'm harsh, strict, sometimes evil. I must say that I don't do evil things like regularly but I feel the need to punish those who deserve it. I never pick on weaker than me or anything similar but I lost all my emphaty long ago.)

The question is: I want to cleanse my soul, body and mind from everything evil in me. Not necessarily negative, since I'm not a negative person. Also big problem is that I don't feel guilt for what I've done since I think people deserved it. (Tbh I didnt do anything horrific but still, I should have ignored it/be more mature/or just approach things in nice way) How and what do I do?