If you dont respond to this situation in the way you would have done before he had cancer then his disease has claimed 2 victims.
Your relationship as well as his health.
I knew that Robin hated me treating him differently after he became ill,so i didnt.If he yelled i yelled back,if he was self absorbed i reminded him we were both in this thing together and although i had my health his cancer had my life too.When rob was in the hospice i once said to him"just because you are dying doesnt mean you can talk to me like that" he laughed and laughed.
Maybe its time for a bit of normal marriage behaviour he may be looking for that to reassure him that he is no longer someone you are pitying.