Let it go!
Oh boy did I! I forgot to write a paper for my English class. It wasn't that big a deal, not even worth a grade. It was just a sample writing piece. But I felt like such garbage. I let out a yelp in the empty Quad of Brooklyn College this Sunday.
Then when I got home later, I was playing a game. I had just created a nice piece of weaponry and was swapping it out for and older piece I had been playing with for a while. I knew I could sell it to another player for a lot of money. Then, I accidently sold it.
OMG did I almost break my keyboard. Then I realized I had just thrown away imaginary money so it wasn't THAT big of a deal. Yelling at the pixelated shop owner for a second helped though. :)