Oh Twig....I am so sorry to see your post this morning. I have been wondering about you & Riley & am sharing your tears.
About 5 years ago I lost one of my beloved pets under much the same circumstances. She was a beautiful & loving Irish Wolfhound named Millie who was a huge part of our family. She was 10 years old which is old for that breed but far to young for us to lose. She had heart failure and reading your story reminds me so much of her final day.
She was so weak that she couldn't move herself at all so I set up her blankets with all of her goodies on the floor and my two kids and I sat with her. There was always at least one of us with her. I remember my kids even brought their homework over so they could be near.
Our other dog stayed by her side as well and by the end of the afternoon our cats had joined us too. It was amazing really. Because she was so big and we couldn't move her easily to relieve her I had our vet come to the house & put her to sleep with her head on my lap. It was one hard thing to do but she was safe and finally comfortable and knew that she was loved.
I tell you this because I want to let you know that I understand very well what you are going through. Not much can ease your pain right now. CDs suggestion about lighting a candle is great, I did just that as well. Saying a prayer for her safe passage and imagining her in my mind as the goofy, romping dog that I knew running around with a whole pile of new friends in the summerlands.
I was (& still am) convinced that sharing a love like that in your life is a forever thing & that I will, in some way, shape or form, see her again. She is buried on our land where she is with me everyday. I haven't done so yet since a lot of work needs to be done around that area but but I plan on planting a tree by her. Maybe you could do something like that for Riley....perhaps a pecan tree
We all cried so much during that time. I remember having a constant headache. As I told my kids at that point that crying was OK..."a shower for the soul". Which is not a bad thing.
This will be a hard time for you coming up. Know that my thoughts are with you & Riley for both of your comfort. Take care and be well.