NTA NTA NTA

He left you and your mother, never made an attempt to contact (at least you don't mention in your OP) and therefore he has no entitlement to anything. If you don't want to speak to him and don't feel like it, just don't. Also I don't know where you live, but at least where I'm from, you're responsible for your parents when they're old. When they need nursing care you as the child must either let them live with you and nurse them yourself or pay the cost for a nurse or even nursing home. I never knew my father and made sure to collect all documents possible so I don't have to do that when he gets old and sick. I'd recommend the same.