I borrowed this from a friends wall on Facebook, it was originally from this link . I totally agree with the sentiment behind it. When you are performing a piece of music, yes it is great to get all the notation correct however sometimes this does not happen. In the times when it does not go the way you want it to it is the self confidence in your ability and the push to carry on and not stop that will make the performance.
The most important thing in a performance is the rhythm, or the continuance of the rhythm and the beat no matter what. If you make a mistake, which you may do, the mistake itself is not the problem. It is the stopping, or stumbling, of the rhythm that causes the issue.
Therefore accept it, that mistakes may happen, strive to prevent them but if they do occur, keep going. Most of the time an audience will forget or not notice the mistake by the end. Unless it is at the end, to prevent this do extra practice at the end.
A performance is an act, not just in playing but with the performer too. Rock it, own it and put on self confidence.
You can do this, you have put in the work so go and give it your all, or at least "act" that way. Enjoy the show, you deserve it.