Being upset serves no useful purpose. I would spend some time figuring out how it happened, how it could be prevented in the future, and then I would DECIDE, make a conscious choice, to not think about it any further.. what is done, is done.. I would change my focus to something positive - for example, that I wasn't hurt etc.. we all make mistakes, act foolishly, are imperfect and weak, we all do stupid things - point is that there is no point in INDULGING these thoughts, which only make us miserable.. getting upset keeps you stuck in the past. Thinking positive, changing your focus, gets you 'unstuck'. When your mind goes back to being upset, change your focus again.. what we think is a CHOICE that we make.. every waking moment.. make the choice to always be positive, to always see the positive and you will be happy. Why? Because positive thoughts create positive emotions - that's how emotions work. It's the only way they work.. Always think positive, self affirming thoughts, and always treat yourself as you would your own best friend.