I think something probably
is wrong, but it's
not your fault. Sounds like you are beating yourself up over it, and you have to STOP that immediately. Saying that it is your fault is such a twisted self-hurting thing that I (and probably a lot of us here) have done for so long. You need to change that and have only loving, compassionate thoughts about yourself and about everything you do/not do.
One thing that is most likely "wrong" is that you triggered insulin spike and believe me
nobody can fight that, it's a super strong force; how do you think we got to be so obese? None of us loved how our bodies were starting to look like as we were gaining and gaining, but no one could stop. The only way to beat this thing into submission is to take a few days aside, and calm your insulin down...the hard few days, yes, and maybe it will be 10 days, but that's what you got to do and then there will be no need to cheat any more, regardless of what your other feelings are. And like everyone pointed out, each and every time you feel down, this place will cheer you right back up.
And yes, it is helpful to analyze "what's wrong" but no more "what's wrong with me".