What is the ruling of the Shari'ah concerning a husband who does not believe in his wife's infidelity despite conclusive evidence, and continues to live with her, amidst accusations that he is bewitched or a cuckold, and his father's threat to disown him?

If your brother is afflicted by sorcery, then work on treating him with legitimate ruqya, guiding him and his wife with wisdom, and preventing strangers from entering his house. Your brother must understand his responsibility for guiding his family, for Allah Almighty says: "O you who have believed, protect yourselves and your families from a Fire" (At-Tahrim: 6). Teach them and discipline them with what will save them from the Fire. Provide spiritual nourishment in your homes through the texts of revelation. If the wife repents, there is no objection to keeping her; but if she insists on immorality, it is better for your brother to separate from her.