Is your biological father alive, and do you have contact with him? If so, let him know what is going on. Also, tell your mother exactly how this man makes you feel (that you're terribly afraid of him). Tell some adults at your school as well, so people will be aware of your situation. If your stepfather has hurt your physically and there are marks, immediately tell people at school and they will take photos. Then they will call Child Protective Services. Do not just stay quiet. If your mother is afraid to say anything to him, then you have to protect yourself. If nothing else, when he does something, go to your nearest fire station and tell the firemen what is going on. Fire stations are considered safe havens. A lot of people don't know this. They will keep you safe until something is done. Check to see where the nearest fire station is to your house. You can go there day or night. Something will be done if people know what is happening, but you have to let them know.