I Hate him so much, but I can't deny that I still have feeling for him

He's used to be my Best friend, but now we separate, he have a girl friend now, which she used to be girl friend from my another best friend, I hate him so much, because of her, he's avoiding me, we used to be close, he always there when I need someone to talk, he always make me laugh of his joke, that's why I love him, but now he's different, he's not the person I know again, why should I do?? i really want we back to as best friend again, but when i saw he face, i really wanna stempel, punch his fucking face