You're going to lose your daughter acting like this mom. Have you sat down with her and chatted about sex and its importance in a relationship and birth control, etc? Or are you just the judge and enforcer? I was 18 once -- in college AND sleeping with my boyfriend at his apartment. I eventually married him. If my mom had called me a tramp.... well I don't know what I would have done. I don't know how you can talk to your daughter like that. What is she supposed to say when she's half asleep and her mother is calling her at 4:45 and calling her names? I would have hung up on you.
The problem is, we don't know what your daughter's story is. Is she a good kid? Is she in high school or college? Does she have a job? Is she respectful to you? Does she help around the house? Could you ask her to leave and support herself if her lifestyle bothers you?
Whatever you do, please stop calling her names. And to all the women on here aghast that an 18-year-old is having sex while still living in her parents' house....seriously? You all need to join the real world.