I feel like a horrable person, am i the bad one?

No u are not the bad person, but u should grow up and stop pouting whenever u cant get ur way. U should have never let him ride with ur sister without u. Only u know ur sister. She is the one that should have stopped feeling whatever way she may have been feeling when it came to u and ur boyfriend. Remember a guy is going to be a guy especially when they are pushed away as you did him. If he is for you and u care for him stop throwing him away as if he doesnt matter. Eventually he will go else where to feel loved. hope this helped