i have been ruminating about an event that happened when i was in fifth grade what do i do to fix it?

hello. This event happened when i was in fifth grade and for context im in eight grade now close to graduating. There was this one kid that slapped me and in response i pulled on his hair but it still feels like i didnt do enough to avenge myself (i did defend myself against him later on by kicking him when he was teasing me in and sixth grade tho) which he himself admitted that it hurt him alot but i dont know i still feel like a loser. Any advice????