I wish I had a clue how your wife is going to handle all this!
My own story is kind of funny. I'm sure my therapist realized early on that my mother was the original of a lot (not all) of my "problems". He never point blank said that. He kind of sets things up so I can find them for myself. There was a time, last fall, when something happened and I suddenly realized "Wait! What my mom just did.......If someone else did that it would mean..... Actually, I don't KNOW anyone else who would have done that..... 'Normal' people don't do that? Does that mean my mom's more nuts than I am???" At my next session I began by saying, "I think I've figured this out, my mom's crazy isn't she?" There was a brief pause. Then he burst out laughing. Then he said that, while he objected to the use of the word "crazy" yes, in fact he was quite sure my mom qualified for more than one official diagnosis. If she ever availed herself of the opportunity, which she wouldn't.
In my family, apparently, it was my job to be "wrong", There doesn't seem to be any way to change that. My dad was ok. Except that he adored my mom and probably couldn't see a lot of what was going on as a result. The fact that he WAS ok probably saved me, to a point. So I hope it works out that you can, somehow, stay in this girl's life. The rest? I hope you wife gets into therapy and things go well. It took me over 2 years to realize that I wasn't the actual problem in my family. It's still kind of hard to wrap my mind around. I think she has to figure it out for herself. Especially because it sounds like she's more inclined to look for someone else to blame than I tend to be. (My first reaction to EVERYTHING is to assume it's my fault.) If you try to talk to her, more than likely she'll just take it wrong and turn it back on you. I think all you can do is be as available as she'll allow, as stable as you can, and stay out of the drama. Staying out of the drama, as much as you can, is probably really important.
More than anything, I wish no one ever had to go through this stuff!