How can one deal with a husband who neglects his wife, prefers his sister over her in everything, controls her life, and insults her and her family, despite his intense love for her to the point of possessiveness?

A husband's care for his sister is commendable, as it falls under the category of showing kindness to relatives. The husband has the right of guardianship over his wife, so he may prevent her from going out without his permission and compel her to wear modest clothing. It is not permissible for a wife to spy on her husband, as the Prophet, peace and blessings be upon him, said: "Whoever listens to the conversation of some people who dislike him doing so, or who flee from him, molten lead will be poured into his ear on the Day of Resurrection." One should overlook the husband's shortcomings and deal with him with wisdom and affection to preserve the marital relationship from the whispers of Satan.