(((ruby))), you are not the only one who struggles with carbs! My advice to folks is always this: be kind to yourself in this. Beating ourselves up only makes us feel bad about ourselves and guilty, which really doesn't help much in the long run. Carbs are addictive to so many of us, they are all around us, and it takes more than willpower to manage the problem. You may have messed up one day out of five, but that means you did great four days out of five--give yourself a pat on the back for the success, too!
Every mistake is also an opportunity for learning. Now is the time to ask yourself some questions and brainstorm some solutions. Can you eliminate carbs from your home altogether? If not, can you buy carbs for your family members that you really dislike--even if only for a couple months? If even that isn't possible, can you install a lock on a cabinet door and keep the carbs in there and only give some other family member a key?
Now, what else do you think triggered your eating that bowl of cereal? What had stopped you other mornings that didn't stop you that particular morning? Journaling carefully on this can help you see the triggers--which may be emotional or physical. (Sometimes, a legal food that is dangerous for you, eaten the night before, can trigger next-morning cravings)
Sounds like you are like me, in that if you cheat in the morning, it is nearly impossible to stop the rest of the day. So maybe another lesson to learn is to defray the cheat until 8:00 p.m.--at least it will just be one meal then, and not a whole day! Try to be perfect, but if you are only pretty good, also try to congratulate yourself for that.
I admire you for sticking with this through the struggles, continuing to post, and not just running away into full-blown carb eating. As long as you keep progressing and hanging in there with us, you will conquer this.
You're stronger than that bowl of cereal!