Protecting one's mother

I know that Islam gives most priority to the mother. If my father is a bad guy and continuously does very rough behaviour with my mother, then what can I do? If I also am rough to my father for the sake of my beloved mother to protect her, then will it be a sin? What can I do? My father tortures my mother both mentally and physicaly. I have attempted a lot to make my father good, but still he is a bad one. Please tell me, in this case if I hate my father and do rough behaviour when he scolds my mother for nothing, then will it be a sin?