Don't allow yourself to go there. Don't even allow yourself to think about bad grades because those thoughts just lead to more anxiety and depression. Try to remind yourself that you are ready for these exams. You can write! You just expressed yourself quite eloquently. I know, it isn't the same. You weren't under pressure. Still, it is there. Proof that you can focus. So, tell yourself that. Picture yourself succeeding. Dwelling on future failure will almost guarantee it. Even if you don't believe it, every time you have a discouraging thought, try to follow it with the truth, which is that you can do this and you can do it well! Stay positive. Hang in there. Focus on success and the feeling of relief you will feel when it is over. Good luck!