You fell off the wagon. You can spend time beating yourself up, which may make you give up, or just give yourself a pep talk. Recognize this is a way of life that involves decisions. This time you made the decision to have some dessert. You may have concequences from it such as a little weight gain, or cravings, but you beat them before and can again.

If you look at it as a diet and cheating, then you set yourself up for failing, or at least beating yourelf up alot. Instead recognize that there are good food choices and bad. Occasionaly we make bad ones, but as long as we are prepared to deal with the concequences it's ok. It only is a problem when the majority of our choices are bad ones, then we need to figure out why we are doing that to ourselves.

It will also help for next time to plan ahead. The 4th of july is coming up, and I think everyone has a problem halloween through new years. Next time maybe bring a dessert of your own to share with everyone, host the dinner yourself, eat before you go, or come up with some other game plan to see you through the night. If you do chosoe to indulge, then have a small piece and savor it instead of a large one, eating fast before your concious can catch up to your hands