Someone please listen to me

I'm a middle schooler, and something really awful happened today that made me so angry I took it out on someone. But please let me explain. I've always bottled things up and endured a lot of unpleasant and sad experiences, but today I reached my breaking point and kicked someone. I know it's partly my fault for letting myself be pushed around, but I think to myself, 'Don't you dare think I'll always be a pushover, you idiot!' There has to be a limit, right? But they didn't even realize it and kept provoking me unreasonably! Doesn't that seem really unfair? I did apologize to the person I kicked, and they forgave me, but I'm still so angry. Is there anyone who can relate?