I bullied a guy in our school
Why did you bully someone at school?
Yes. I just got tired of him picking on everyone!
Even if he was a bully himself, two wrongs don't make a right. Even if the other person deserved it, you shouldn't stoop down to his level because bullying is never the answer.
Now that it's over, I'll forget about it.
I understand that you might want to forget about it, but this type of behavior has negative consequences and you should realize what those are. You should reflect on why bullying is bad and how you could have handled this situation differently to address the bullying that initially upset you.