Many people feel, at the last moment, like they've under-prepared and they're going to fail. But these feelings are just that, feelings. All you can do is revise hard and try to get a good grasp on the course. It sounds like you've been doing that. Your thoughts are not you. Your emotions are not you. If you've done a lot of work, you've got this. Trying to cram things in at this point is generally futile; you can go over your notes in a leisurely fashion, sure, but don't strain yourself. I'm a finalist at university. Yesterday I was stressed about an exam a couple of hours before it, and felt like I should be doing something. But I knew from experience that at that stage everything was basically set, so I just put on Netflix until the exam started. I was relaxed, and it went well. You want to get a good night's sleep, and you want to relax yourself. Everything else should come from the work you've done. In any case, good luck!
Edit: Also, if you need to cry, nothing wrong with a good one of those. It's your natural method of releasing emotion under stress and almost invariably will leave you feeling better in the end.