Hard to deal with dad stage 4 temper

My dad has stage 4 colon cancer at 62. He is currently 118 pounds and doing radiation after brain surgery.It has spread to his spinal fluid and chest wall. My dad has always been verbally and mentally abusive to my family. I honestly don’t like him if we’re gonna be truthful. We are currently taking him to appointments and he is horrible to deal with. Flat out yelling and berating my younger sister who has TD1 and also has a hard time dealing with his emotions. How do we deal with this? I fear it’s causing my mom and siblings already mental health issues (which he has caused over the years) to be even worse. Advice?