I know EXACTLY how you feel. But I wish I knew what to say to make you feel better. I'm sitting here on Halloween eve while my 'friends' went out to a haunted house. I was never asked to go along. Halloween is my absolute favorite holiday and they know it. What's worse is that I live with them. Sad thing is, while they're my closest friends. I don't trust them enough to tell them anything personal. If you ever need to talk, feel free. My wall is empty.
Let us know what happened. It would help us understand. I think it has happened to many of us. Sometimes, people are jerks and it's not about you. It's about how inconsiderate they are. Cheer up. You will make new friends who could turn out to be better friends.
I don't need to know what happened... I usually am the one left behind trying to get away from everything slowly disappearing in the sea of nothing...