I also get serious anxiety attacks and some times panic attacks. The best advise I can give you is don't forget how to breath! Breath! Take in some air and let it out. Hold it in for few seconds before you let it out. This actually releases some chemicals in the brain to help ease anxiety. The other thing to remember is the people in your class are just a quick blimp in your radar. They really don't matter that much in your life. And worse case scenario is you may be too nervous and some people may find that funny which is ok because all do stupid stuff some times and it's forgotten the next day. Oh, almost forgot, drink plenty of water too! We all feel worthless, that's the lie anxiety tries to sell us. Good Luck!