Stay friends or tell him?

so i like this guy and his names kumar, he has a sister named keyshia and for some reason she doesn't like me well their really tight and i don't wanna ruin that but i really like him and idk what her problem is so i'm torn do i tell him i like him and i go from there or because his sister is a B***H i just drop it i mean she doesn't even wnat a us to be friends but we still are and he never goes against his sister so what do i do try to remain friends or tell him i like him and get my a** kicked