What is the ruling on going to the home of the wife's father, whose daughter left the marital home because the husband refused intimacy due to a health excuse, after the husband's repeated oaths of divorce that he would not enter? And is the wife divorced or what?

Any oath you made involving divorce is considered a conditional divorce, which takes effect upon the fulfillment of the condition it was tied to. Your wife's father inciting his daughter to disobey you is forbidden and constitutes the prohibited act of "takhbib" (incitement to rebellion). We advise you to be gentle with your wife, considerate of her weakness and illness, and to remind her that her disobedience is a grave sin that forfeits her rights. If she does not respond, it is permissible for you to divorce her due to her bad character. Divorce may be permissible out of necessity, or recommended when she neglects the rights of Allah.