Step away from the ledge. Relax. After two years of law school exams, I can think of very few that I have come out of thinking "man, I nailed that." The great thing is that you don't have to nail it, you just have to do better than the rest of the people. As a result, as long as you felt comfortable about your preparation going in to the exam, that is as good as you will ever feel about an exam. In other words, if you felt like you knew the stuff well and you still felt that the exam was hard or unfair, odds are that you are not the only one, and more than likely, others came out feeling worse. Just put it past you and go on to the next exam.