You don't have to allow that to happen but the only way to take control of that is to disconnect from him.
I agree with this statement wholeheartedly. I will add, however, that disconnecting takes on a myriad of forms. I have been on the verge of going no-contact with my parents several times in my life.
I, too, worry about their end-of-life issues. It's complicated, but should either of my parents die, I will (legally) end up being the one responsible for them, so I figure it's in my best interest to stay involved in their lives.
However, I don't have to stay
emotionally involved. I can check my emotions at the door, and let things wash over me. Granted, it's taken a lot of work to get here, it still takes a lot of work to maintain, and I still get side-swiped at times (when I let my guard down), but I recover much more quickly and the emotional sabotage doesn't stick.
I sometimes think that going no-contact would be much much easier. But I would not feel true to my own moral/spiritual code of ethics if I was to do that, so I put effort into learning how to not be affected by them instead.