When I arrived home with the milk my sister expected me to be upset. It felt good to walk in quite the opposite. She smiled her "I-owe-you" smile, y'know the one we all have to smile once in awhile? Well, I smiled right back, a genuine, no-longer-sleepy smile.
I will try this more often, it felt better than looking back on what happened and getting angry all over again, and it felt better than looking back and realizing how petty I was. Dinner was great, and I had not a HINT of heartburn.