I think you can really make the guilt work in your favour....
If you've finally snapped and eaten something you shouldn't have, the way you're feeling about it now means your cravings for that food will be gone.... for a while, anyway. And since you're feeling so guilty, it's not like you'll cheat like that for a long time. Now you have extra motivation to diet really strictly, and keep it all clean.
Had you eaten that ice-cream and not felt guilty, what's to stop you eating it again tomorrow?
The guilt is a good thing.... you've given your metabolism a kick, you've kerbed the cravings for a while, and you've given yourself new-found motivation to diet properly.
Those 3 pros combined, outweigh the single con (2,000 extra calories) for sure.