Friend getting abused by mother (or so she says)

I’ve never posted in a group before so bare with me here. I’m currently in 8th grade (I’m 14) it’s about the middle of the year and let me just tell you, my school is a lot. Recently I’ve joined a group of girls I know in my 1st period, they’re not my closest friends, but I’d say they’re pretty okay acquaintances. One of the girls I’ve noticed has always been kind of the outcast, she’s unreasonably happy, she has no access to media, and she’s just a bit different. She began to complain of her braces hurting, we then started giving her advice for it. She then OPENLY, like I mean out of nowhere, tells us her mother had backhanded her in the face. Out of shock and worry we quickly started questioning her. She mentioned how her mother always hits her, and that she tells her kids these days are “soft” and that what she’s doing to her is helpful. Her mother’s way of “counseling” her is throwing her against a wall, what she calls “wall to wall counseling.” It’s so much more than physical abuse, she has no access to media WHATSOEVER, she can’t have a school iPad so she has to sneak it, which I feel a the mother’s way of keeping her from finding out what she does is bad. She then tells us we can’t tell anyone, that if she does her mother will beat her. Last time someone did her mother beat her because CPS came. Luckily my friend behind us had told her counselor what she was overhearing, she convinced me to go as well. I’m actually extremely close with my counselor so it wasn’t as nerve racking as I thought. After I’d mentioned who the girl was, I then noticed she’d slouched in her chair, like she’s been through this. She then explained to me that I’m not the first person to do this. In the beginning of the year 4 other people had reported the abuse, the counselor and principal then met with the mother and her. My counselor didn’t exactly tell me what, but she’d lied about something. She’d lied about her mother’s abuse, how can that be? There’s a few clues I’ve noticed though, I don’t really know this girl and we’ve maybe talked once, I wouldn’t tell a random person I don’t know that I’m getting abused and then tell them to not say anything. She was almost comfortable with the situation, like she was open with it and okay with it.

But I don’t know what to believe, there’s really nothing I can do. Do I try to help her find proof? I’m gonna try and voice record our group session tomorrow to see if she’ll mention it again, but in reality....it won’t tell me the truth