Why does my friend hate me?

i know that his older brother Drue torments him with his fists, but i just don't get it, he treats me like i'm a great big steaming pile of poo on the sidewalk... he's like my best friend and i have always treated him with respect, i haven't done anything bad to him, yesterday, he slammed the door in my face and told me he doesn't care about me.... i feel like a loser now. does anyone have a suggestion of why/how this is happening?