First start off with a pumice stone, every time you get in the shower use a pumice stone, before you know it your feet will be beautiful.
It's 30 minutes of no talking. You will live through this experience. Trust me. Learn from this and move on with your day.
Yes, tell your parents. You don't want it coming up later on and them find out by accident. Then accept your punishment. It is a minor infraction, with a minor punishment.