Help! How can I stop feeling nauseaus about having to eat in public?

On Friday I have to go to this formal banquet with a three course meal, and I am already nauseaus just thinking about it. I always have this problem, especially with this one guy who invited me this Friday to the banquet. I don't know why I said yes, but I am sick of missing out on stuff just because I can't eat in public. Whenever I get even a little nervous I can't eat, now I get nervous because I am scared I can't eat. I am going to have to eat on Friday or I'll fully humiliate myself. I am in desperate need of help!