Quote ......"I shall be both devastated & elated in equal measures when the inevitable happens"
2112, I think I know what you mean. It was the same with our family when both mum & dad passed away. Dad had a tumour in his head that was causing him great pain for a good while, eventually going onto a Morphine drip/syringe driver, in increasing quantities for about 8 days. When the inevitable happens, it seems as if a great weight is lifted from your shoulders.
Despite the grief you also feel happy that there is no more pain & the person is at peace.
With mum, she was 101 years old, & over the past 2 years had slowly declined & was bedridden for the last 18 months. Getting weaker & weaker by the day.
She was in no pain, but was put on one of those syringe drivers (not sure what was in it) because she had problems swallowing & it was to relax her & make her more comfortable.
Again, after 4 days of that she passed away peacefully. Again devastating, but a relief.
Neither wanted to go into hospital & neither did, as our 2 younger sisters, both nurses, took it in turns to give them both 24 hour care.
The family owe them both a great deal!
You & your good lady are doing great just by being there.