Welcome back home =)
I went on my honeymoon cruise a few years ago with the same best intentions. With thoughts of "its' a vacation, not a vacation from good health" etc, etc. Believe me, it's very easy to fall off the wagon when the wagon's no where in site.
That's why most vacations are short. Fun was had (hopefully more than food fun) and we come back to normal life and return to normal ways. Don't spend long beating yourself up. We're human. We do these kinds of things from time to time.
You're already taking steps towards getting back into the groove.