First of all, forgive yourself. You made a mistake. Guilt causes no weight loss at all. Guilt can (and often does) lead us to more comfort eating or self-punishing eating. The guilt, in other words, is worse for you than the food you ate.
Many of us are addicted to the brain chemical cocktail that high carbs (especially eaten alone) give us ... we're addicted to the foods we're allergic to ... we're addicted to eating for comfort, solace, to numb pain, to punish our mothers, and a hundred other emotional reasons ... and we're habituated to old familiar habits, too, like eating popcorn at movies. This can be helpful to remember.
None of that makes us "bad." Food has no moral component. If you're a good person in the rest of your life, don't rob banks or beat children or the like, no amount of overeating food could possibly make you "bad."
Once you've dumped your guilt and gotten calm, figure out why you made the mistake. (What triggered it? An event? A smell? A sight? Spending time with someone who stresses you out? A fight with your teenager? A painful memory?)
Brainstorm how to deal with the same situation next time. Write down this plan.
Apply one or two of those ideas next time the same situation arises.
If those don't work, add to your list and try other approaches to this particular trigger.
Remember, you can't "blow the diet" because this isn't a diet but a permanent way of eating. Part of a WOE is finding strategies for dealing with challenging situations. As long as you are learning something from this experience, you're still moving forward.
If the cheats seem to become chronic, you simply can't stop, it's tearing you up inside ... then think about finding a local OA (Overeaters Anonymous) meeting. Their website is here