First, get back to a typical routine of three small meals a day with a healthy snack or two in between.
Third, get back to your exercise routine. Several gyms in the area are having January specials. Look into joining and kicking off the new year with a healthy exercise regimen.
Finally, don't be hard on yourself. If you cheat one day, then you are normal. We all mess up; but it's the ones that can get back up and try again that succeed!