Do you think this was alright for me to say to this guy?

This kid threw something at my head on purpose and i completely flipped out on him. I said "I swear i'm going to kill you." I didn't mean it, but i was pissed at the time. And then i turned around and said "if you do that again i will go up there and kick your ***." Do you think that was a bad way to approach it. I'm a girl, so i hope that i didn't embarrass myself. I didn't want to tell the dean, because it was the last day of school anyway and plus i wanted to show him that i dont take crap from anyone. I just feel like the only way to stop people from annoying the hell out of me is by telling them to stfu or give them what they deserve (dw im not a physical type of person haha). Was this a good thing to do at the time?