Sounds like you lost a good dog. Tough loss; the more you love them, the more you mourn their passing. My brittany is 11 1/2 years old, and has health issues. When her time comes, I hope it's in a similar setting as you've described. You gave her a good life; you were with her at the end, and her passing was sudden. No doubt she left your family with lots of good memories to help everybody through the sad days. Best wishes...