Welcome to the staying board!
I don't really know anything about EMDR... . and my wife recovered through a combination of things that probably aren't repeatable for anybody else, so I won't give you full details.
One part was her realizing she was being abusive to me.
One part was me enforcing boundaries to prevent the abuse.
One part was mindfullness meditation (which we both did).
The final piece was part was a workshop that helped her deal directly with her own self-hatred.
And most of it was hard work on her part, facing really tough stuff--I'm proud of her. It was over a year, and it was hard on me and harder on her. I think that one big reason I was able to stick around was that I could always see that she was even harder on herself than she was on me.
We do have an article on treatment; I recommend you read it if you haven't already:
BPD: Treatments, CuresAs for helping her find a new T, if she acknowledges BPD, then interviewing a T and asking about their experience with BPD is a good idea. (If she doesn't, then think long and hard before you speak of it... . we have a big topic on that too.)
How involved in her search for a new T are you?
How involved does she want you to be?