Does a husband who is not equitable between his two wives and visits one of them as a guest have the known rights of a husband, and is the wife sinful if she cuts him off completely, especially after he informed her that he would not change his ways?

The husband's failure to deal justly between his wives is a grave sin and warrants the warning mentioned in the Hadith (definition): "Whoever has two wives and inclines to one of them more than the other, will come on the Day of Resurrection with one of his sides fallen." However, this does not permit the wife to boycott him or withhold his rights. She should advise him and remind him of the Islamic ruling. If he does not become just, the wife has the right to seek a divorce or to refer her case to the judiciary to compel him to be just or to separate them.