This has happened to me before. I remember a few summers ago everyone in the group acted like I was a monster. I'm not a social person and often times I'm very shy and passive. But I don't get why people have to act Like that. Maybe someone made a rumour about you or maybe they're just being assholes. Surely you could find someone to like you. If not, then try to make friends outside of school. Take classes at community college, get a job or get to know some of your neighbours. Don't let those jerks bother you unless it starts to get out of hand. Then take some form of action.
Sorry but I have a hard time believing that your principal just walked up to you, kicked you, expelled you, and talked shit about you for literally no reason.
Good luck!