In my own personal opinion, the majority of us here are codependent and we are struggling to recover ourselves. If we knew the answers to your questions we would not be here. This is like going to the AA forum and asking them how to deal with an active alcoholic. They will all tell you that each person needs to work on their own recovery and not someone elses.
We can each tell you how we are dealing with our own recovery, but could not tell you how the people around us are dealing or how they should deal with it. In my opinion, she is doing the right thing by not dragging you into her mess because she needs to figure things out on her own. The best thing you can do is be there when she wants to talk about things and don't pressure her in any way. She probably doesn't know how to have a healthy relationship or it flat out scares her. Most of us codies need chaos in our life to feel normal.