Hiya Debbie
You said be honest so here goes. I can completely understand why you feel upset about all of this. It isnt fair of your daughter to move without telling you and you not knowing where the little one is after you worked so hard to help when they both needed it.
I also think that because your daughter has been so dependant on you, with the diabetes etc, she may have been feeling that she couldnt just be sponteneous and go. She has been swept off her feet, in a pleasant way on one hand, but I do not doubt youre in her thoughts, she will want to reconcile it all and probably didnt want to throw away the house in front of you as she felt guilty'. She was thinking with her heart instead of her head. I have an Aspergetrs syndrome son, who has just become a father, he has always been quite dependent on me in the 'counselling sense' but he has flexed his wings and kind of said, up yours, I can do this. I kind of grieved for this need somehow but on the other hand I am pleased for him.
Please dont shut yourself out of the lives of these beautiful people, you have helped so much to nurture. Get your glad rags on, paint a smile (I have had to do this many times) and get yourself in there. Slog it out and smile again.
Lots of love and hugs