Your options are either 1)do badly in the rest of your exams 2)pick yourself up, slap yourself in the face, get on with revision and do the best you can in the rest of your exams. Hopefully, and if you have done badly - which you probably haven't to the extent you think, you can make it up with your other papers and subjects.
So, stop mopping. Go for a run or something, chill out for a bit and then get back to the grindstone.