Failing

Why does the feel of failure feel so gawd damm heavy?
I feel like a black cloud has taken over all of my emotions, my thoughts and my inabitions and just left me blank.
I had an exam today and felt really good going into it. I had revised a lot more and just felt completely comfortable with my memory recollection. Only things turned upside down and i completely blanked. I couldn't recollect any piece of information, even that i only looked at half an hour ago. I continued to keep going, filing through my brain, but in the end i tried and i failed. Trying= Failing after all.
I came away feeling utter disappointment and my self worth crashed. I couldn't give my self a pat on the back or celebrate my fullfillness because i failed. My brain failed me and i'm not used to that, educationally. I suppose i became more accustomed to the fact that my brain is failing me in more ways than just my emotional/mental health state.
I need to try harder in the future to come as now i realise my brain is going to need a bit more work and more elbow grease in order to function to my previous standards. I will not fail in the future. I will not let this feeling of worthlessness en capture me.
-Rachel