i absolutely agree with you. I also felt awful after 2ck. I went in feeling very well prepared, and I went out feeling defeated. But my end result was Ok. It was not as I expected but was not as bad as thought it would be.
Since there's nothing you can do now, just forget it and focus on the things that you should do. Cheer up! Give yourself credit for your effort and for being able to finish the exam.
My 2 cents for those preparing for 2CK, do NOT underestimate 2ck. in my opinion, it is more difficult than step 1. I had 15 mins left in every block on step 1. I barely had 5 minutes left on 2CK. It's doable, but not one you want to take lightly.