Hi, I just got out of a situation just like yours. Have you tried a christian counselor yet? Do you think she would be willing to do this? I went through the same thing for almost nine years. He even divorced me once, then came back and wanted to marry me again. I did, but that was a mistake. I am really paying for it now. I gave him the option of counseling he said yes but when it came right down to it he refused.
Try asking about the counseling and mention (maybe ) that this is a last chance for you guys, and see what happens. Keep praying for her though. I felt the same way you do, that this is right in the sight of God, Read 1 Corinthians 7:10-16 and see if that helps any. God doesn't expect us to stay with someone who doesn't want to really try, or wants to go ahead and live the way they want to even at the expense of the relationship.
I will keep you in my prayers, God Bless