Ellen braved it out on Sunday with her piano recital. That "butterflies in the stomach" feeling hit her Saturday night and even deep breaths could not completely rectify the situation. Personally, I think the best performers are those that get a little nervous before the performances - it brings out the best in them. Also this feeling causes us to practice more and be more prepared.
And what a great feeling of accomplishment when the performance is completed. Mistakes (if any) are now in the past - completely behind us. Some angst about the errors - not me unless I'm feeling guilty about not preparing hard enough. In most cases the audience doesn't know enough to even recognize any of the small errors (after all we can be our own worst critics)