First, SarahBell - here is one big, big, hug from someone who walks the same road on the same journey.
BUT YOU DID NOT let yourself down! You are human and have emotions. You do not start the IP program being programmed to be perfect. If that were so, you would not have the opportunity to learn from mistakes.
Whatever you have done in the past day, past week, or past month is OVER and DONE WITH. Goodbye, sayonara, au revoir, adios, ciao, tschau.
What matters is the moment now as you are beginning a new part of your journey on the program. Clean slate, no recriminations, just new resolve.
You can do this, even with children and spouse around eating other things.
Think about something special you want to do when you reach goal. Picture yourself doing that, wearing something special and glowing with health. Keep that picture in your mind and when needed, take a deep breath and remember that picture and how exciting that moment will be. It will feel ever so much better than whatever may be trying to make its way into your mouth when it should not.