I played at a half major concert. Not a concert hall, but quite a big hall in a school. I was just a small small part of it all, so no one really cared about me. Anyway, I felt quite sick already (and next day I found out that I had the flu *yay*). So, I was playing, and suddenly I got all dizzy and everything turned black for a few seconds (probably not that much, but you know how it is) and I skipped like an entire page. And then it happened again, that everything turned black and all, so I decided to play a cadenza, and then be done with it. It really wasn't my proudest moment, and I cried so badly the whole day after the concert.
But, piano is like basically everything else. Either you chose to just leave it, and never play it again. Or you suck it up, cry a river (build a bridge) and get over it.
I think a part of the difference between a good pianist and a profesional one is the way they get over things like that. Ofc, a real concert pianist doesn't screw up that badly, but you know what I mean...