Hi pollybree,
I'm not going to lecture you on breaking the diet, as I'm sure your beating yourself up enough. But maybe take some time to think about why you did it. Are you trying to sabotage yourself in some way, are you scared about the surgery and what it entails, are you REALLY ready? Maybe finding the answers to why you did it will be more beneficial to you than worrying about what you did. I know I was petrified from about a week out right up to the last second, not about the surgery but if I was really ready for my new life. I've struggled with my weight and had an eating disorder for more than 20 years, finding new ways to cope without food was one of the best things I've ever done and I was lucky enough to do this before the surgery. I'm really nervous about who I will be and how my friends/family will be with me when I'm finally a healthy weight- but that's for another day and Im rambling, sorry!
Whatever you do I'm sure it will be the right thing for you,
Good luck hun,
Jen x