Hey, Peaches, let it go! So you over ate today. *shrugs* It happens to everybody occasionally, including skinny people. Just eat a little lighter for the rest of the week. Do not try to make it up in one or 2 days. Just eat maybe a 100 calories less each day.
First though, TRACK IT! I know, it is scary, but you need to see what you did.
2nd- STAY OFF THE SCALE! It will show a temporary weight gain. Don't be discouraged by that.
3rd- Understand that you will have good and bad days. That's life. Shrug it off and keep going.
4th- Repeat after me. "If I don't want to restart, I must stop quitting".