Gaffed - Messing up something really big; you were almost there, but

Messing up something really big; you were almost there, but then you messed it up so bad you want to cry

I was so close to passing the test, but I gaffed it and got a D

I almost won the game, but I gaffed it and lost

I was about to get the job, but I gaffed it and got rejected