Help with sexual harassment in the home.

My biological mother, lives with an “ex-pedophile” as she says. I’ve told her there is no such thing, but she refuses to listen. I still have two younger brothers in the home ages 17 & 19. The elder of the two has a girlfriend that stays over at my BM’s with my brother frequently.

She was still a minor when the first incident occurred, he’d grabbed her a$$ as she was leaving one afternoon. Then not long after he started calling her sex, baby, honey etc. The harassment has only gotten worse. Last night he’d cornered her in the hall way and he’d told her “I’d fuck you if (name) weren’t here” on several of these occasions she has called me freaked out.

She is now afraid to go to the bathroom at night. What should I do, I know what this guy is capable of. And my BM doesn’t care. I seriously feel this girl is in danger. He is registered in a different county, and living with a minor. I’ve reported him many times and each time he gets away with it. She’d stop staying the night but that the only time she can see my brother. I’m at a loss, any advice would be great.