Dear Dr. Kate ,

My teen age son is 18 and still lives at home. His father is out of the picture and I try to be supportive of him while he is getting through community college classes. It's just that recently he has hooked up with this 23 year old college drop-out named Emily. She comes over and stays 3-4 nights a week and his grades have been suffering. She is basically a nymphomaniac and I hear them upstairs in his bedroom having sex at all hours of the day and night. Sometimes I swear they don't sleep at all. He often seems tired but is too embarrassed to talk about it with me. I want to tell her to leave, but I'm worried it will just drive my son away and to her apartment across town. What should I do? -Concerned Mother