Oh, Set, I am so sorry.
I can understand that big hole in your heart.
My 15 year old dog died in January, after several months of being significantly infirm and disabled, and my own heart still aches with loss. My only relief was that she died at home, of natural causes, and that I didn't have to euthanize her, because I think that would have devastated me even more. I am glad that Cleo was also with you until the end, with your presence, and her familiar surroundings, to comfort whatever distress she might have felt. And I am glad you know it was a peaceful end for her.
Sincere condolences to you and Beth. Everyone who has ever loved and lost a dog knows what you are feeling right now and can empathize with you.