Once we convince ourselves that we ruin everything we touch it's hard to ever believe otherwise. You ought to look at these situations and ask yourself some questions.
Is it REALLY ruined, or is that just someone's opinion?
because it may not be that you ruined something legitimately, perhaps you only believe that you did because something didn't go the way another person thought it should, and why does that person get to decide what's right in that situation? Who made them boss? Maybe that person is trying to do something they shouldn't be. or maybe they think everything should always go THEIR way?