Your post was one that brought a big lump to my throat.
Others here have offered some terrific insight, and I doubt I can add any fuel to keep this fire going, but I'm sure going to give it a shot.
I will start by underscoring what Sage said: I really don't see you being back at square 1 at all. You've got 2 years of a very successful history that proves you have good insight and knowledge in how to turn things around.
I don't profess to have all the answers. BUT if I were CAW and the one who wrote that letter (and 2 years ago, it would have been something I would have written), I would want to be validated and understood.
Personally, the quickest way to get me to think about the reality of my decisions and the consequences they might have is to concede without any argument. Give me what I'm asking for. I can promise you the fact that it was too easy is going to make me ask myself some really tough questions.
CAW sounds like a complicated woman--that is, not one who can walk away without thinking either.
(((((KAW)))))
I realize that you didn't want to be in a position to choose door #2. Since I'm here myself, I find this extremely disturbing... Tell us more what you did the first time. Would letting her go with your blessing (at least on the outside) be a 180 for you?
At this point, I see that you are exhausted--mentally and physically. Perhaps you feel you were fighting a battle, only to lose the war? I hope not, because your victories were valiant and with great purpose. This time, would you want CAW to come back of her own free will? I know that would hold great appeal for me...
What do you (and anyone else think) about using your DB knowledge and techniques while letting her go? Not fighting so hard, but to let her fight things internally in her own theatre so you don't get sucked into the emotional drama once again? See if she asks herself if this is really what she wants and make her audition for you?
I don't know, KAW. All I know is that I see a really swell guy who has fought brilliantly and with courage. And no matter what decision CAW makes, I really see you as a winner.
Please feel free to come over and kick my butt if you need to... and a big hug to you today.
Betsey
"There are only 2 ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle."
Betsey 
