If your dad has a computer, go on it, get some type of keylogger and spyware program to monitor what he is doing, hopefully he looks at lots of gay research, or at least straight research. Once you build up a solid case, print multiple copies and hide them in many places, not just in your house at school and in a safety deposit box. Show your dad one of the copies and tell him you have many more and he better start learning who the boss around the house is before your mom accidently sees a history of his internet usage lying around the house.