Andy,
You probably don't want to hear from me again but, I'm having a tough time understanding your situation. You can get mad at me if you want, that's okay. I have a difficult time making the right call when I don't understand the question. In order to get the correct answer I need you to break down all of the information that you can. How many players? What betting round? etc, etc. Your initial question indicates to me that there is more betting to follow. If that is the case, I see no options other than calling any bets in front of you (with your exposed hand) or taking any action that you would normally take if no mishap occured. That would include checking, or betting, or even raising with your cards exposed for all to see. You may still win but, I sure would feel uncomfortable if someone called. If you expose your hand, you can not declare yourself all-in and play for any portion of the pot, unless you really are, all-in. If I missed again, then I'm afraid I can't help.
Andy, whether the cards remain face up or not is irrelevant, as long as they were announced and the remaining players know the rank and suit.
Stuart and Chet, I need your definition of passive play. Thanks