Belated Welcome!
The women before me have given solid advice. Something I want you to think about in terms of "Falling Off the Wagon" <---- banish this thought. There is no wagon, just as there is no diet.
Here - I want you to think about diet in these terms alone for the rest of your natural life:
"The diet of the koala bear consists strictly of eucalyptis leaves."
From now on diet is not about what you dont eat, but about what you DO eat.
Follow me?
As for the wagon - meh... You are making a LIFESTYLE change. So one day... hmmmmm in the grand scheme of the rest of your life we are talking about averages here. So if you have A DAY where you dont make the best choices or function at 100% why would you beat yourself up? Don't lose sight of the forrest because of the trees.
Does this make any sense to you?
If not, then just say so and I will try to explain it another way.