First, try and not get yourself into that situation, so it doesn't happen again. Second, I think you should try and discuss it with the guy, suggesting that you are uncomfortable with the situation. If he shares more information than you currently know, then you make a decision.

I'm sorry this happened. There is a good posibility he was as drunk as you. Anytime we are out of control, well, we surrender control to others.

(((hugs)))