Don't worry too much about it. Many people have this problem.
I was once afraid to talk in English too, but my fear gradually disappeared. I think the best way to gain confidence is to put yourself in a situation which requires talking in English. Do you have a chance to go abroad, for example on a student exchange program? Or maybe you know a native speaker who would like you to show them your city? When it's just you and a native speaker, and nobody else, you just have to talk. And you don't have time to think about your mistakes!
Anyway, you will become confident eventually, if only you don't give up. The first moment is always most difficult!