Ha, I did the same thing. The first few months after I got engaged I actually endulged in a lot of delicious foods...knowing that I was going to have to stop eating all of that at some point. I feel like having one last hurrah with the yummy stuff before I said goodbye to it for awhile made it a bit easier!
Try to set a date and an action plan - like I'm going to start x day, and I'm going to lose x pounds per month, and I'm going to do it by having a x calorie diet and burning x calories per week through exercise. It's totally do-able if you do the calculations of how many calories you need to get rid of per week/month (3500 calories = 1 pound).
Good luck!