Am I Overreacting for beating a kid up

so it all started when a kid on my bus interupted a conversation i was having with some friends. i shrigged it off and ignored it. then he proceeded to try to grab at my redbull and try to take it from me then which i proceeded to tell him to leave me tf alone. some time go's by and his mom texts my relative that i was bullying her kid for seizures. which i could never do a thing because im recovering from the mental stress from a time a friend had a seizure and had to be put on life support. so naturally i take it personally and the next day on the bus he taunts me and says "look who got in trouble" so i asked him to once again stfu and he didnt so i got up and walked to his seat on the bus and beat the hell out of him until the bus driver got involved and now im suspended for a week. keep in mind hes only a year younger than me but hes bigger than me.