the behavior you describe may be abuse and neglect. There should be a child and family services department or department of health in your state that enforces abuse and neglect laws. You could call the police department or report through your local school counselor, or call the department directly. You can report anonymously, and your identity should be kept secret. Such things do leak out though, and your father or mother may retaliate. And, If the social worker investigates and finds neglect or abuse, you and your siblings may find yourself living in a foster home, or split up into several homes. The abuse you suffered years ago would be taken into consideration. Both of your parents could lose custody as your mother divorced this guy but then lets him live there. Visitation rules are meaningless if both parents are living in the same house.
Is there an adult relative you trust that you can talk this over with? Or do you trust a school counselor? This is a lot to take on yourself, so you want to be sure. Best to talk to someone first.
DISCLAIMER: The forgoing comment is for general educational purposes only, and is not legal advice upon which the reader may rely as the commenter has no actual knowledge of the facts of the case, has not interviewed persons or examined evidence, and has not researched the applicable law. The comment is based only on the facts provided, which are extremely limited, and may or may not be true. Complete defenses may prevent the success of any claim. Competent legal advice should always be obtained before taking any legal action or filing suit. Readers employ any information provided herein at their own risk.
A weekly guide with tips and legal advice for each stage of the process.