Worried about a strangers relationship

So, back in February I had this girl message me we’re going to name her Lisa, Lisa is dating a guy a used to date Austin (idc about his name being out there he’s a dick) my relationship with Austin is that I had to deal with sexual abuse from him, and him being completely obsessed with his ex “Chloe” let’s call her that. Well Lisa has messgedme asking me had he ever been aggressive towards me, and he has. He was violent. He was evil and so manipulative. I’m in no ways trying to make this about race as I’m a black woman, so is Lisa and Chloe. He is white- and he loved to throw the N word around (with the hard R) and calling black people monkeys like it was nothing. He was a jerk. Well recently Lisa messaged me about Austin, and I’m kinda worried for her, he got her pregnant she already has a child with another guy, and her baby is just now 9 months old. The same thing with Chloe (his ex) Chloe messaged me a while back telling me about how he gave her two black eyes and broke her nose, after I had went to her about him. He can be so vindictive. He messaged me through Lisa’s FB a while back telling me to stop talking to her. I worry about her so much, but I’m so scared to message her first, like what if he sees it? And the reason why I’m so invested in this is because everyone in my town knew of how awful he was, even some of my friends! I had to find out the hard way that he was not what he said he was, I just wish someone had told me he was abusive. I wish I had known about what he did to Chloe, like everyone else did, before I went to her & found out who she was. I would’ve ran and stayed far away from him had anyone told me he was abusive, I’m not blaming anyone for what happened. It was my responsibility to learn more about him, but it would’ve been nice to have had a heads up about this guy. Like he is CRAZY...and that’s why I worry about Lisa so much, that’s why when she messaged me I was more than happy to talk to her and hear her out and tell her every last detail of what I went though. I think he’s back with her, and though I understand that it’s her responsibility to leave, it’s not that simple for some people sometimes. I just saw him comment something on her Facebook, and she replied- this was after that whole incident. I want to message her and I want to help her, but it’s not my place. I just don’t want it to be too late before he ends up possibly doing worse.... I’ve happily have moved on, but I just can’t sleep right knowing that he could be doing worse to her and idk how to get her to leave. I don’t. 🥺 it breaks my heart for her. I don’t want her to turn up dead or missing.