What is the religious ruling regarding a wife's dealings with a husband who frequently insults and curses religion, falsely accuses her, threatens her, instigates problems, swears to divorce, has excessive sexual desire, and legalizes what Allah has forbidden?

What you mentioned about your husband cursing the religion and making lawful what Allah has forbidden are grounds for apostasy, which necessitates the dissolution of the marriage. If this is true, then he is in grave danger. His case should be referred to the competent authorities or the Dar Al-Ifta (Fatwa Council) for clarification and to question both parties. Cursing the religion is disbelief by the consensus of Muslims. Making lawful what Allah has forbidden, if it is known by necessity to be forbidden, is disbelief by consensus. Accusing chaste women is a grave sin. Speaking ill of the wife in front of the children is harshness and bad manners. It is not permissible to marry two sisters simultaneously. Swearing by divorce is not permissible.