It might seem really harsh to say this, but what she's doing seems like manipulation to me. She has a place to go, and she won't go there, I think maybe she knows that she can get you guys to falter if she keeps it up long enough.
It must be very difficult to be in such situation, I can't imagine what it's like, but I hope you know that you can't change a person, and that none of this is your fault, regardless of what action you do or don't take. She has to face some hard truths, and it sounds like she doesn't want to, that is her choice.