Everyone has the audition that went nuclear. For reasons known or unknown, the music you thought you knew suddenly felt beyond your ability.
The only way an audition is a complete failure is if you don't use it to learn. It's alright to take a day to be disappointed, but then you have to go back and examine what happened. Deconstruct your audition prep and how things went the day of your audition leading up to the performance. See where the cracks started forming long before you walked in front of the audition committee.
Then plug them up.
Failure is discovery. Choose to see that failure as an inoculation. Now you are aware that when you do ________, it means you won't play your best. You can take steps to avoid it next time. Try going through The Audition Checklist to see if there were any steps you missed or could have done more completely.
Most importantly, don't use this one instance as a judgement of your playing as a whole. On that particular day, at that time, and on those particular pieces, you did not do well. But next time will be better.