Completely agree with Morrigan there.
I would also say, if the meal is for an occasion, relaxing for an evening and not worrying too much might do you good. Find something tomato based that you really like, then don't panic. You'll feel satisfied, and ready to crack on with the diet the next day!
The sudden rare peak in calories means that your metabolism is likely to work overtime for a while, and actually help towards your diet, as long as it doesn't become a common occurance!