"don't know why I'm telling you this because there is nothing you can do or say to help but I want to tell the story I guess."
What we can do is listen to your thoughts and understand that you know your dog best and whatever decision you make is out of compassion towards your mate. Sometimes talking about a problem helps our thought process to rationale the problem.
Animals have an uncanny ability to adapt to pain without reflecting pain from symptoms like humans handle it. I had a cat who died from cat leukaemia. It's a hard decision to euthanase whether the pet has been with us one day or 13 yrs. You both enjoyed an extra year of each others' company, and I'm sure Mrs H's also. Your mate is blessed to have such caring owners.
I hope for her what I'd ask for a human...comfort with her remaining time and strength to you and Mrs H when she decides.
