When I was in middle school, I remember seeing a question on the board and feeling positive that I knew the answer. When all was quiet and the teacher asked if anyone knew the answer, I confidently spoke up, only to be incorrect
Oh no how did you feel?
An odd combination of wanting to die, and not wanting to exist. Like, I basically wanted to reverse time. 
I totally understand that feeling and know what you mean! But I wouldn't sweat over it, it happens to the best of us and we learn fro our mistakes!