When it comes down to it, Alpha, we are all doing what WE need to do. I know that they are upset, but as the other gals said, it's because you're awesome! I would be upset too, LoL. But you gave them as much notice as you could. 2 months is pretty decent.
Bottom line is; being upset or feeling guilty isn't going to help, nor will it change anything. Enjoy your last weeks with this group of kids, and get excited about your move. This is also an opportunity to make any daycare changes that you may have thought about. You can alter your hours, set up the play space differently, whatever!!
Congrats, my dear, and GOOD LUCK!!!