There isn’t anything you can do while she is convinced there isn’t a problem.
Im quite sure her family life wasn’t great and you can paint a long and tragic tale, but do you want to continue to be part of it?
You don’t have children with her and one of hers is now an adult and the other is old enough to know better. You are right to feel hard done by on that front.
Part of the problem is you keep bailing out her bad decisions. So much so the consequences of her actions don’t belong to her. She already is convinced you will go back to her if she creates the right situation and promises the right things.
The daughter’s attitude to cocaine appears to be a financial one. Which means at some point she will either get on it or look for other options between the price of weed and cocaine.
So, I’d say, leave her. No doubt she will try things to get you back, but while she is happy to abuse so many substances and doesn’t see it as a problem, there isn’t anything you can do. She needs to reach an emotional and consequence low before she will even consider changing and that isn’t going to happen with you around.