I finally got over my nerves by changing my focus to the audience rather than the judges, or myself, or my partner. You've done the work! Try to think of it as the time to really enjoy it. I dance much better when I am less intense about perfection (a few good comps will reinforce this). It's funny, but if you imagine that the crowd is loving you, and you manage a little eye contact with a few people, you will be surprised...not only at the unexpected positive feedback you will get from total strangers, but also the confidence it gives you to be a more natural, and better dancer.