My child is 25 and didn't have kindergrad, think it started after and it always seemed silly to me. Not so much an achievement but a made up sort of one. He did wrestling thing in 4 & 5 th grade, at the end of the two month wekly practice ( and what a kick that was to wastch) they had a meet with everyone getting a medal. The second yr he had to be out of town for the meet so the coach just handed him the medal. He looked really sad, like why get this for nothing, it meant nothing. I made up he was "most improved" which helped but it brought home that kids do not need medals, awards, graduations "just because" but for things they have truly earned.
I know having the rest of the parents there and you not must make you feel incredibly guilty, but don't. At the least, you have shown your child it is ok to make mistakes and indeed he/she will most likely love to spend quality time with just you more.
Edited, and your child will have a long and happy life, with this being such a minor blip in the larger scheme of their life.