Alright, lemme give some context. I am in highschool, and my friend and I like to go to the school basketball games to kill time and get away from home.
At the beginnning of one game, my friend and I split up, as he wanted to hit the concessions stand, and I wanted to find a place to sit. I didn't see him for half an hour. I was getting bored with out him, so I went back to find him. I found him fuming at a redneck kid and the kid looked pissed. I went over to someone nearby, and asked what was going on. He said that the redneck kid had called my friends sister a n****r. He and his sister are mixed. I'm pretty close with both of them, so I was pissed. 
Apparently, my friend had roasted the kid, and he got salty. Roasts became threats, and now they were about to rip each other apart. 
Soon enough they began to fight. My friend hit him in the face first, and the fat kid retaliated by hitting him in the temple. He was pretty hefty, and I could see it jarred him, and I figured he could use some help. I jumped in and kicked him as hard as I could in the side of the knee. As he collasped, I kicked him a couple of times, and his mom ran over and began screaming at us, and we booked it all the way back to my place.
After the adrenaline wore off, I began to think about it differently, and how I should of just broke it up. 
AITA?