Help! My friend may be in trouble!

I have no clue what to do. I'm worried for my friend. My friends step dad got her high with laced weed and did things to her she thinks.She said she was hurting really bad down there yesterday and wednesday he got her high and she can't remember anything. I'm not in it. It just worries me.He's been asking her to do things for a while now. He has held her down naked while her mom is at work. She told her mom and her mom insisted she was lying. She chose to stay with him. My friend is extremely suicidal and is worried her stepdad did things and may have gotten her pregnant. What do I do? I'm the only one who knows, so she will hate me if I tell. I feel so lost.

***UPDATE***

I've taken her to the hospital, and they sent her home. With guess who??? Her stepdad. Her mom makes her and her younger siblings lie to dcfs so she and her husband don't go to jail for the things they have done. They have recorded her doing things, and their mom found out, forced them to delete the recordings, and threatened to send them away if they didn't. She told the hospital everything and they SENT HER HOME.

***UPDATE***

She refused to tell anyone. She doesn't think it's a big deal. My mother and I made an anonymous call to dcfs last week, and they've done nothing.

***UPDATE***

Her period is 4 days late now. She thinks he may have not pulled out like he said. She has no way to test. Her mom refuses to let her leave the house. The only time she gets an escape at all is when her mom works. But, when her mom works her step dad is home.