Oh Diana, I am so sorry. I can't imagine how sad you must be. You have always been an incredible DIL. I can tell because of how hard you've tried to connect with her. (Like that special 3 day personalized gift you bought her.) It's really sad that she has not appreciated you for the wonderful person you are. I know it sounds cliche, but SHE is the one missing out. Really. I know I have been touched by your friendship even though we are miles apart...she could have had a great friend and family member in you, if she would only try.
I'm sure your children are hurt by this decision, but at least they have you and you have done so many things to make their lives more special and meaningful. That is something they will never forget. They are lucky to have you and I'm sure they realize this, especially in light of how their grandmother is treating them.
Again, I am so sorry that this happened. I'm sending you hugs!