Mental harassment

What happens if a husband is mentally harassing the wife? I just wanted to know if there's any law that says anything about verbal/mental harassment in a marriage To his friends and outsiders my father is a "very good man. my mother should consider herself lucky to have a husband like him". Only I have seen how he really behaves with my mother. To outsiders she now looks as if she's lost too much weight - she looks haggered. She never told her parents anything when they were alive thinking it would be shameful. Now she is scared to do anything because she feels that if she tried to take any legal action - my father would get ger out of the house, and leave her with no means of taking care of herself. He has mistreated, verbally abused her. The minimum my mom expects is to be treated like a human being. My dad treats her as if her sole existence is to look after the house and not think for herself. My plan is to save money so that atleast the years she has left in her life she will be able to breathe. DISCLAIMER: my father behaves in this way only with my mother - they are incompatible, like polar opposites. He behaves in a very patient way with outsiders so it is confusing to me why their marriage is like this