By no means is this my worst choke, but since it happened to day it is by far my most memorable one.
I won the first set 6-4 relatively easily but should have won 6-2 but choked a couple of games. I was serving at 5-4 in the second set when there was a questionable call followed by a disagreement over a let due to a ball in the court. I had a partial mental breakdown and ended up losing that set 7-6, and a tie-breaker for the 3rd set. I only choked on 2 match points but one of them was over-hitting on a second serve return which I really really should know better then.