My long depression

I am still sad about my last exam result.
For the last few days I've been thinking that it was pointless - those hours at the library (so, I haven't done anything for the upcoming exam yet). Well, I know that in the end I had fun. I mean I loved the subject, I loved that I had so much work to do on my own, I loved my professor... But now I kinda think that I did not get what I deserved for my hard work and it hurts inside of me whenever I think/read something that reminds me of the subject. I guess I will understand it more when I think about it for some time.
That's kind of strange, but I think I will still do my best next time. Next time...