My Step Daughter Told Me Something Horrifying

I always had a feeling my step daughter may have an issue with eating. She doesn't eat in front of people, and tends to look at herself in the mirror a lot. My husband (her dad) wanted to her to start seeing a therapist but her mom is refusing sayinv she's fine. I was talking to her last night about her body and asked how does she feel in it. She said she hates her body and how fat she is. She's not even fat. She is a bit thicker but not fat. She said she's working on losing weight and her mom taught her how to get rid of it. I said "Get rid of what? The weight?" She said "That and the food" that sent off so many alarms. I wanted to ask what she ment but also not push so hard. Should I tell her father about this conversation. I'm really worried for her because I used to get rid of the food when I was younger and anyone with an eating disorder or had one knows what that means...