The important thing is don't beat yourself up over it. Consider what you've accomplished just by gathering your willpower together and fasting for 4 days! My first Master-Cleanse
crashed and burned after almost 8 days, and although I caved in a moment of weakness (tuna!?! for pete's sake- tuna!), I didn't let myself dwell on it as a failure. I got a decent cleanse out of it, but more importantly I accomplished something just by staying strong for that brief time and resisting (most) temptations.
If you choose to continue, stay positive and don't think about what you might be "missing", because as you said, you didn't even WANT those breadsticks, you weren't even hungry. Remind yourself of this when you fast in the future, don't let yourself feel deprived or miserable just because you aren't eating.
Ultimately, I know that my first fast wasn't considered a "true" Master-Cleanse
success, but more than anything I LEARNED. I learned a lot about myself, and I also learned about how to make my future MC's more productive.
So DO NOT consider yourself or your 4 day fast a failure! Rest a few days, a few weeks, however long you need... then get back on the wagon! You know what it takes, you're willing to do it, and next time you'll be able to get through those weak moments by reminding yourself how disappointing those breadsticks were! :)
I waited almost 3 months before trying again, and this time I was READY. I can tell you with utmost certaintly that this fast is A BILLION times easier than the first, I am so glad I decided to try again. I am better prepared and the biggest difference is the positive attitude I have adopted about the fast. Be glad you're doing this- you body will thank you later!
Good luck and congrats on making it 4 whole days!