Awful.
My grandma had alzheimer’s. We let her disease run it’s course, as awful as it was. And she died with me in her bed snuggled up to her as she drew her last breath. I hated how out of it she was, and I know she would have been embarrassed if she had any clue how she behaved in those final days. But I’m not God. Neither is my dad; there was never any talk of “pillow treatment” or anything like that So, we just had to deal with the cross we were given to carry. And that’s what we did. She was treated with respect & dignity until she died a NATURAL DEATH.
Death is rarely dignified; but dignity is the way we live and a large part of that is treating the dying with dignity. There is NO dignity is hastening a person's death.
Death is almost always painful, in various ways. Love and respect, like that shared by your family, helps to mitigate some of that pain. Killing only magnifies the pain. The best any of us can hope for is to be surrounded by loving people when our time here is done.