For anyone who wanted to follow this, I decided what to do...
I called my friend and left a message on her cell phone. I told her that I was concerned for her safety, and that I knew she was spending a lot of time with my ex. I said that I wasn't sure if she was dating him, or just friends, but either way there were things she needed to know about him. I ended it by saying that she could call me back, but if not, I really hoped that she would be ok...