I recognize the behavior because I have an addict in my family, and I had to separate myself from him, just as you said. It’s the only way to be safe and keep your family safe.
And it is actually better for them. Gives them some time to self reflect. They will initially harbor anger because you walked away (How dare they do that to me)(That hurt my feelings) etc. etc. About the only way to cure them is to let them know you are on to their ways and their ways wont work anymore. Actually had one recently admit, yeah it was their fault because they were being the jerk. Took a lot though and would rather have not done it.