First, sorry to hear of your loss. It seems that if this were the best of all possible worlds, there'd be no reason to entertain philosophy from an existential standpoint.

With that said, I think factually, you'd be OK'd to euthanasia in countries like Switzerland or similarly, other countries that aren't hostile towards the concept.

What prompted you to ask these questions, @Ken, if I may as in more detail?

I have become very forgetful lately. This may be caused by my grief but I have to recognize that I was becoming forgetful before my loss. Less so but still forgetful. As part of my loss, I realised I didn't want to spend my final days helpless in a national health hospital or a nursing home.