What do you do if the whole school knows who your crush is?

You've got basically two options:

1. Curl up and die from embarrassment.
2. Get over yourself. Nobody actually cares much who your crush is, with the exception of you, possibly your crush, and probably anyone who's crushing on you, if any such person exists. Once they quit laughing ... a couple of days, or a couple of weeks at most ... it should stop being an issue.