Maddyee, I am very sorry your dad is ill. Both of my parents are gone so I know the feeling of loss. I also know the feeling of being helpless because of their choices about their end of life decisions. Both my parents were very brave to not only make these choices but to stand by them when the time came for each of them. They were only in their 70's when they each died, too young, but life choices lead to it. They could have continued living actually, but, chose non-treatment. They both died without pain and peacefully, surrounded by those that loved them. We could have at any time protested and interveined, but, that wasn't their wish. We honored their wishes as their children. We all still miss them, but admire their strength to such a commitment. I only hope I can be so brave. They too were private people, didn't lean on others.
He is your parent, of course he is worried about you, that is what parents do. You said he may no longer be a candidate. Can you speak with a coordinator to confirm this? Liver donation has a lot more risk than kidney donation. Could he get a cadaver liver? He might consider that rather yours if it was presented to him.
Frankly, I think in his case that your kidney will be a very hard sell. But, you can try, but don't waste what time you have left fighting over it.