Hi Patty.
This is very sad. He could choose to be a role model to the family on death with dignity but he has chosen a much more selfish path. Of course it's easy to attempt to second guess what must be going through his mind. He must be very frightened and helpless and this is how it's manifesting itself. Myabe this is the role model his father gave him.

Maybe you need to try an intervention with a clergy, other cancer victim, or even close friend. It sounds like he could be greiving his former life; confusion, bargaining, anger, depression, and finally acceptance, are all components of the 5 stages of grief. They don't alway occur in order and sometimes occur simultaneously.

If it's a non smoking houshold I would be setting some appropriate boundaries.