Regardless of why she is doing it, it’s wrong and she’s an adult who needs to take responsibility for her actions.
My addict partner is abusive and I’ve had enough of it too. As far as I’m concerned, regardless of why he is abusive or why he does drugs, most people do not go round treating others like this. It’s unacceptable. He has to take action to admit what he does that’s wrong and the problem/s he has and take actual steps to deal with it. To that end, I’m waiting to be rehoused as I can no longer live with him.
I think you have done well to draw a clear line and boundary of what you are not prepared to do or accept. At least you are not enabling her.
Does she live with you in the holidays? If she is going to be abusive towards you then you are perfectly within your rights to not allow her to live with you and the same goes for if she were to use drugs in your property.
If she is willing to accept what she’s doing that’s wrong and take steps to deal with these issues then that’s something you could at least work with. It doesn’t sound as if she is willing to do that at this point in time. Blaming you for not enabling her is quite a classic behaviour that I’ve experienced and seen others reference on here. It’s always everyone else’s fault except the addicts when they are in active addiction and struggling etc.