My question: What exactly are my responsibilities toward him?
Praise be to Allaah.
It is not obligatory for a woman to serve her husband’s father or mother, or any of his relatives. But it is the matter of chivalry and good manners, if she is in the house, to serve his parents. But with regard to forcing her to do that, it is not permissible for her husband to force her to do that, and it is not a duty upon her. What I suggest is that the wife should be patient in serving her husband’s father, and know that this will not do her any harm; in fact it will make her more noble and more loved by her husband. And Allaah is the Source of strength.