I am so sorry Luna is gone. I know how it is to lose one fast and not know why. I also know how it feels to lose your first grey. As far as the boys, they will start picking up some of her jobs/responsibilities/habits, and that will help them with the loss. Most of the time they deal with death better than we do, and they knew she was sick. It's no surprise to them. At our house, we let them see the body. As far as people, you need to grieve in your own way. I feel it helps to write about her... nice, cute, funny, special moments... and GT is the perfect place to do so. Talking will help, but the man here does not talk about them for a while because that is the way he grieves.
Sending hugs,