I think what you are doing is perfect. She's not going to like it one bit, but must have some sort of feeling you know something based upon the questions she's asking.
You might call a friend to help out with the kids tomorrow night. It could be a challenge as I'm sure she's going to flip out when she realizes the bakery with the cake just left town.
I think I'd just pull out the manilla envelope and not pull the trigger on the D petition quite yet. Store your bullets cowboy. The envelope is going to have quite the impact I think.