Kiki, it's times like this I think of an analogy CatsPajamas uses often..."If it's outside my hula hoop, it doesn't belong to me". Picture your hula hoop around you and then look around, you'll see what she means.
What matters here is what works for you. Obviously this whole arrangement does not. Kiki, she can take care of herself and her child if she really wants to. If her living with you draws you into her life and triggers you, then that's unhealthy for both of you.
Maybe give some thought to letting go, whether she continues to live there or not. Declare your daughters free to make their own choices...even bad ones just like you and I made before we learned. Then step back and grab your hula hoop and make your own world pretty once more.
Hugs