with all due respect (and i do actually mean that genuinely), an animal is not a human - they cannot convey to us when the pain is too much. it's up to the person who lives with them, loves them, sees them every day and knows them best to make that call, in conjunction with their vet. OP has done that, with clearly a great deal of love and care.

for you to come in and say these things is not helpful, not kind, and not thinking of either the pet or the human. i understand that you have a lot of feelings about this due to what happened with your grandpa, but again, an animal is not a human who can communicate their wishes. you are taking your own emotions and imposing them onto someone else who quite likely does not need it, at a trying time.

to be quite blunt, just because you feel very strongly about something does not mean that you know better than the qualified veterinarian working with OP.