KAW - you have been a greater help to me than you will know, as I have lurked (and been brave enough to post a few times) for quite a while. I, unfortunately, am in almost the exact same position you are, save for the letter.
I'll post details on my thread in a bit - just wanted to tell you what I think - for what it's worth:
Let her go - lovingly.
Try to understand that she needs to see what "it" is like. Perhaps understand is the wrong word, since I don't think I will ever truly understand what my W is after - perhaps accept is more appropriate.
I read somewhere (maybe your thread?) that dropping the rope is a great analogy - eliminate the tension, she does need to see that you are NOT the cloud that hovers over her - her perceptions are.
And as hard as it is to acknowledge, think. Do you REALLY want to keep on chasing somebody and something that has absolutely no desire to be chased, and will not meet any of your needs? This is the point I am coming to - as much as I WANT my W to love me again, I cannot MAKE her do so.
I hope these ramblings of a confused, frightened husband and father make sense. I truly know that the situation does not. And I truly know that you will emerge from this ordeal a stronger, better and eventually happier man.