Hello and

Rail33!
You have indeed found a place where people understand and have gone through the exact same things...
One thing I've seen is that MANY pwBPD are very resistant to the idea that they need help, and avoid getting it. In many cases, the label BPD is difficult and triggering for them to hear, and makes things worse. Many refuse therapy. Many quit therapy after starting. And many get at least some therapy, and do improve.
Getting her into therapy is a great goal, and if she gets in and does the hard work, it should help a great deal. But you cannot make her go, and even if you could, you cannot make her do the work.
My suggestion is that you try to focus on what you can do about her beahvior (with you), not just how to get her into therapy. There is a lot you can do for yourself (not requiring her cooperation) as well.
Can you tell us a bit more about your situation?
Do you and your wife have any children?
What is she doing that is difficult or hurting you?
Has she been getting worse lately?