(Assumed your five-year-old is a boy, since you used "他", "她").
Withhold and minimize your attention paid to him, just do the bottomline maintenance (food, hygiene, etc..)
Leave him alone, or even deliberately ignore him. Give him a chance to develop a longing for your attention/affection/approval, if he is capable of such.
The time and energy freed up, use them to attend to your husband and treat him as the authority. Let him order you around and act like a "good" wife. Put up a show. If you have contempt for anyone, keep it to yourself, and speak possitively of people around the child.
Whether this works or not, at least you get a chance to remove you yourself as a factor.
Disclaimer: not a professional advice.
