I'm surprised no one else in your class called him out. Bully's have a really dysfunctional way of relating to people so they bond with others by alienating a person. Unfortunately as you and I know, it works. People will side with strength to keep themselves from being that person. I never understood why a group doesn't just gang up on the person who is being hostile and negative. I wish I had advice, but I have been there and you are not alone in this.
I am an old man and have known a great many troubles, but most of them never happened.
Watch your thoughts: They become your words.
Watch your words: They become your actions.
Watch your actions: They become your habits.
Watch your habits: They become your character.
Watch your character: It becomes your destiny.