My boyfriend’s family are terrible people! What should I do?

My bf came from a religious family and was homeschooled his whole life. His father is a child abuser who abused him along with his 10 other siblings. He would beat them with a large wooden paddle until their skin was black and blue and would come off. He starved them. He abused their mother and cheated on her. He got with a young woman from a third word country and brought her to the USA. He believed that a man had the right to have more than one wife. He molested his little sisters. He worked my bf to death as a child with constant physical labor in the hot sun and forced him to pay rent from age 12 and up. These are only a few of the horrible things he has done. My bf’s mom married another man just like his father. This man got with his mother and cheated on her with her own daughter ( my bfs sister) Now the mom, sister, and step dad are living under one roof and his step dad is with the mom and daughter at the same time. I feel bad for his sis she is a good friend of mine. I know she is being abused by her step dad who is now her boyfriend.

Update: My Boyfriend is 23 and does not live with his dad. There are still young children living in his custody being abused. DHR (Alabama’s version of CPS) has been called multiple times and theyhave not done a thing. I only mentioned him being homeschooled because it played part in how much abuse his father was allowed to get away with. His dad uses the bible to justify beating his children, and cheating on his wife.