Why do i feel like my older brother hates me?

my brother and i used to be BEST friends. we are 15 months apart. he is about to turn 14. all of a sudden, he has nothing nice to say to me. he criticizes me, and even when i do something that makes me feel proud, like do really good on the fitness gram like he has always pushed me to get, he says stuff like "so what? that isn't EXTREMELY great. i can do better". it hurts me. i might ask him to help me do homework. he tries to show me. i say "oh i get it now!" halfway through and he will say "no, you don't!" without letting me show him that i do! earlier tonight i asked if he could help me with my itouch as it wasnt working. he completely acted like a jerk about it! as if i was being stupid for not knowing what to do! and he didn't even fix it! my dad finaly did. those are some of the LEAST bad things! sometimes he makes fun of a lisp that i have. just to hurt my feelings! and half the time he acts like I'M the bad guy! i admit, i will yell at him, but i NEVER start it! unless you call asking a simple wuestion starting a fight. the guy just doesn't seem to understand EMOTION! like how people feel hurt when their favorite person in the world is mean to them. my stepmom , mom, stepdad, and dad all ask why i let him bother me. they say i should just ignore him and that he isn't worth the energy i put into trying to get along with him. he does make me cry on a regular basis with the HORRIBLE things he says to me, but i can't detach myself from him. i love my brother more than anything in the world. he treats me like i'm s. please help me! i've tried every trick in the book. from ignoring him, to avoidance, to politeness and walking away. NOTHING WORKS! :'''(