high school relationship advice please!!!

so i like this guy, and he likes me back. he told me last night that he thought about us, and that he wants to be with me. except..... we are from two COMPLETELY different social groups. i'm with the smart kids and he's with the "popular" kids (they basically just go to parties and stuff). but i'm afraid that we're going to get sooooo much crap for being in a relationship. i know one of his AND my friends likes him.... and some other girl i know likes him too. my best friend also told me that his friends will probably shit talk me. i like him so much, i'm not going to throw our relationship away because of some hurtful comments.... but what should i do if it happens? also, he's my best friend's brother. she already knows i like him, but should i continue on with the relationship? i don't want thinks to be awkward between her and i if we break up. this is my first relationship, his too, but he's already done things and i haven't. help!!!