It's such a shame to rid the world of your talent just because you have stage fright. I know that feeling; the feeling of wanting to be able to do great on stage because you know you are more than capable of it – but then comes stage fright. It starts in the stomach as you feel just a little bit upset, then comes the cold sweat, the profuse shaking, then the dreadful fright; the fright of failing or making a fool out of yourself in front everyone, the fear of not being able to convey the emotions (for actors), not being able to hit the note (for singers), and all the other grimi details. Next thing you know, you have set yourself up for great failure before you even began, if you still decided to go through with it (the show).
If it will help you, know that the world's largest stars still get stage fright; they just manage it well enough so that it does not show. Really, it's all in the mind. You can take control of your jitters and use it to your advantage so that it does not get the best of you. That feeling of fright is actually your body's normal defense mechanism when it feels or senses impending danger, whether real or perceived; after all, your body does not know the difference. This sensation actually heightens your senses to give you the ability to perform what it is you need to survive the situation.
There really is no "cure" to stage fright; in fact, the more popular you become, the greater the fear of failing is. Know that you have rehearsed what you need to do well, focus on your performance and not on yourself or the audience, breathe and shake your body a bit, visualize your performance to be the successful hit that it really is, and just blow the minds of everyone in the show.