It's typical to be your own worst critic, but you can reduce this anxiety by learning how to self-critique. When you know how to self-critique, you can videotape your rehearsals and then figure out how to work out the kinks so that when you do perform, it will be an improvement.
Of course, you can't rehearse everything nor can you plan for everything. A live event is a wild card, but if you have the big things taken care of, the cringeworthy performances become few and far between.
So chin up! It's good that you recognize that things need to be changed. That's better than going out, having fun, and calling it a success because it was fun. So, leave that performance behind you and work on making the next ones ones that you can be proud of.