HELP! READ DESCRIPTION BELOW I NEED HELP Please!?

omg this fat guy named deaven thinks he's so cool and he is THE BIGGEST JERK and EVERYONE at my school hates him because he's SO mean and he hates everyone cuz no one will be his friend because hes SO mean and he started sitting with my "posse" [4 members] a few weeks ago and everyone in my "posse" hates him too. ok so today i was sitting by my girlfriend and he starts climbing up the side of the bleachers and starts acting gay- im not saying anything but my best friend (a member of the "posse") [who's like the comedian of the group] is saying stuff and making fun of him, i wasn't saying anything but i was laughing. then my gf stands up and yells (at my friend) why dont you walk a mile in his shoes! and im like whoaa then she gets up and privately talks to him under the bleachers where no one can hear. then my "posse" and i talk it over and think about letting him in our group so he has some friends. when we go to lunch we let him in our group and layed down the laws and he's like you threatening me? and we're like no we're just telling you the rules. our table gets called to go to line up for lunch and he lines up behind me and says this: ok so he walks up to me and says "hey you got that chick (my gf's name but says it wrong and its a completely different name) number?" and im like "first of all its (my gf's name) and why do you want it?" and he's like "cuz she's kinda cute movin up to the hot range." and im like "yeah i know she"s beautiful but lay off she's my girlfriend." and he's like "who cares, i know the rules dont date your friends girlfriend even if they break up" and then he's like "im probably gonna break those rules." and then he's like "you mind if i ask her out" and im like "yeah she's my girlfriend so dont even think about it." and he's like "so what she's hot" and im like "you dont even know her name!" and he's like "so? she's hot" and im like "is that all you care about?" and he's like "heck yeah man!" then im like "whatever just layoff ok?" and he's like "oh when we were under the bleachers i was rock hard" and im like "DUDE!" then he's like "ya mind if i do her?" and im like "what?!" then he started doing the motion and making sounds then went on and on about it and i couldn't take it anymore. so i get out of line and go to my table and put my head down and im taking deep breaths trying to to kill him my best friend and another member were still there and were like whats wrong (while all this my gf is getting lunch) and im like he's OUT! gf comes back and my best friend tells her the jist of it she comes over and says " are you ok? and im like yeah, i cant do it, *best friend comes back from getting his lunch (she was sitting in his seat so she moves back to her table* tell them the jist and they get mad deaven comes back and he's like hey man i was joking and he WAS NOT no possible way i could tell in his voice. im so pist cuz he's a kiss *** and i dont know what to do we're 13-14 and dont say we're too young. and im sorry its so long i really need help PLEASE!!!