I feel overwhelmed and exhausted but he relies on me and trusts me

My name is Trudy and I care for my grandfather. At first I did not want to be in this role but then I said to myself, he relies on me, out of everyone in his life he asked me. He trusted me with a lot, which I found surprising I even have all his bank details, and do his banking for him. Sometimes I get mad with him but then I remember that it’s not his fault that he is old, and realise in those moments that I am just feeling overwhelmed. Everyday I do what I need to do and I just don’t think about it but at the end of the day I feel exhausted. He often talks about things that I would prefer to avoid like death, I can’t handle these conversations but he says to me “ you have to talk about this with me now, I might not be here next year.” It is part of my role to keep him in a good space by staying positive about things. Funnily he used to always be the stable one in the family and in my life, but now I am the stability for him, I guess that is what makes this role so hard.