Harness those feelings, and use them to make better choices in the future!
Think about the guilt/shame/embarrassment that you felt after that meal, maybe even journal about it. What can you do next time to make sure you don't feel bad about yourself next time you are presented with temptation?
Now picture "next time." Your daughter asks you why you don't want pizza or dessert. Picture yourself telling her, that you want to get XYZ instead (salad, salmon, etc), and that you are too full for dessert. Think about how you will feel afterwards, proud of yourself for fueling your body properly, and proud to set such a great example of healthy eating for your daughter.
You can do this!!! Best of luck for your surgery!