How do you react to Mean Mommy moments?

In a hungry, tired, cranky and why-the-heck-is-this-a-snow-day moment yesterday, I yelled way too loudly and long at my older son when he over-reacted to losing at a video game. In my defense, he was behaving very badly, but I should have kept my cool better, allowed him to calm down and then talked to him. I'm ashamed to say that I spent a chunk of the rest of the day (for lack of a better description) kissing his butt and the butt of his little brother, whom I also scared with my loud voice. This was even after I apologized for my reaction, he apologized for his behavior and we shared a big hug. We went to the bookstore so he could read some of his favorites, for example, and made a special trip to the grocery store for a new kind of yogurt he wanted to try. I just couldn't help feeling guilty, as well as a bit irritated at myself about feeling guilty. After all, we're only human as parents and we're never going to be perfect. So how do you ditch this angsty crap (again for lack of a better description) and dust yourself off faster after you've made a mistake?