will i get in trouble if i do this?

[Kittysue]

That's a stupid thing to do. Why not just meet her one on one and tell her you are worried about her. Do not tell her that you want to get back with her. Tell her you wish her the best and are talking to her as a friend since you feel you know her better than most people. Then be honest with her. Tell her that no guy should ever tell her who she should talk to or control her and say that she needs to learn to stand up for herself. You don't want to fight this guy - you want HER to feel empowered enough to leave him because she figures out how controlling he is
Otherwise you can try talking to her parents and say you are worried about her safety with this guy because he is violent and they need to get her away from him