When I was 13 years old I did something very wrong. Back in the day in my middle school was fucked up trend: slaping girl’s asses. I didn’t have the courage to do it myself so when we had family reunion I decided to practice with my 5 years old cousin. When I was playing with her I slightly spanked her butt over the clothes multiple times. Then I continued with slightly pulling her pants down and then I slightly spanked. Once I had pulled so much that I saw her private parts and in that moment I had realized that I messed up. Since then I have never repeated such disgusting behaviour, yet my guilt and selfhate for this action has been slowly increasing.
Nowdays with my cousin I have good relationship, I sometimes help her out with school work. She doesn’t seem to be uncomfortable around me.
Am I a disgusting person?
No, you were an awkward kid. Since you understood yourself that it was wrong and corrected your behavior you’re decidedly not a disgusting person from what you’ve told us here. You however did a disgusting action, one you get to live with as one of those shameful memories most, if not all, of us have. If she doesn’t remember then there’s no point bringing it up. If she ever does then don’t deny it, admit, apologize and tell her you regret it profoundly.
I posit that it’s more so our mistakes and what we learn from them that shapes us than our successes.