I went through the same experience in elementary and high school. I was very shy in university and had few friends. Pretty much the same boat you're in now. At some point I decided to leave my shell and take the chance on developing some new relationships. There were a few hiccups, but I made some real improvements to my social life. I still don't have a lot of friends, but I am getting married and couldn't be happier.
I think what you need to understand is that kids are incredibly cruel. However, at some point most kids grow up and start treating people with respect. You are just going to have to take the chance and meet some people. Take a martial arts class or join a sports team, something that puts a group of people into a casual team-oriented environment. Don't get discouraged if you're not BFF's with someone on day 1.
The bottom line is that this is your life, get it to a point where you are happy and forget what everyone else has to say.