I personally like the approach of the attorney... It is clearly communicating your boundaries and gives the A an opportunity to make informed choices. There is a book called redemptive divorce that explores this path through a biblical lens.
That being said if you in your heart are "done" and you know it then why take that path? If you believe there is hope and you still "love" her (complicated subject as we all know) ... Then a great (not good) counselor might be helpful.
As we know the fairy tale endings often elude those of us who love As... My XA is drinking himself to death in Vegas and my brother got arrested for his 4th DUI last night.
Seek wise counsel... Pray... Follow where your HP leads you....