Work dinner with alcohol

Starfish+77

I need advice. I have a meeting for work in Chicago early next month that I must attend. The one night my team (10 people) will be going to a restaurant for dinner.  This is a normal occurance for us and I ALWAYS have wine. If I say I'm on mess or have a headache I feel like everyone will know, so since I will be just about 10 weeks I'm wondering if I should just disclose my secret then. 

We are taking cabs so can't use the designated driver excuse either. I've thought about bailing last minute on the dinner but I'll need to eat! So any creative ideas out there? Or should I tell the team and ask them to respect my privacy and not share with other co-workers until a couple more weeks. I realize that may not happen anyway.

This situation is unnecessarily stressing me out!