Should I forget it or should I talk to him?

A few months ago, this guy in my grade was talking crap on me. He was saying I was too pale and would be decent looking if I went tanning. I got really upset, because he was saying other things, so I wrote a Facebook status about **** talkers and the fact that it was January, so I was pale. My older cousin, who happens to be very popular and a senior at a nearby school, got protective of me and asked who was saying these things. He got really mad, saying he hoped he saw this boy so he could beat him up and whatnot. And he added him on Facebook to keep an eye on what else he was saying. My cousin even talked to some of my friends and swore that this boy had messed with the wrong girl. The kid at school continued talking, called me an evil *****, and went on and on about how much he hated me. I told my cousin. He said to call him if he ever so much as spoke to me again and the problem would be taken care of. The boy stopped talking crap, and I let the subject drop with my cousin. Later my cousin told me a story of how he ran into the boy at a party, the kid puked on him, and passed out drunk. I took that to mean that my cousin disliked the kid as much as I did and we shared a mutual "F you" attitude towards him. Today, I was on Facebook, and saw my cousin commenting on a status of this kid's, inviting him to hang with him and a mutual friend the next day. I feel very betrayed and unsafe. I love my cousin, think the world of him, and want to keep him to myself. Is he still on my side if he's hanging out with my enemy? Should I mention it to my cousin, or just let it go?