I think in a lot of cases it really does go so much more deep than mere drug and alcohol use. So many of them are frauds, con-men and liars. It's pathological.
I got sucked in this weekend myself, it happens, and now I need time to get back to sanity.
I spoke with my exAGF's ex-husband. He reminded me that, nope, I am not losing my mind when I talk to her, it well and truly is like losing your grip and entering into her own private reality. He's dealt with it for ten years and had his sanity taken apart in various doses.
I don't see it ever changing. He reiterated to me once again that is has always and will always be the alcohol. The denial has become so huge that you cannot being to take apart the layers.