I am sure you will get a variety of answers on "when to go off the path".
Honestly, I can't even fathom the idea that you are considering writing your W a letter. Less than a month ago the gesture of flowers made her very uncomfortable and she expressed that to you. She wouldn't make a year commitment with you for the gym, she is using her maiden name and doesn't even respect you enough to respond to ONE chore you asked her to do for the house you BOTH own. What good would a letter do?
The best path IMO is to lead the way with your W. Let her know if she is not interested in discussing the marriage that is fine but you have decided you are no longer interested in being married without a spouse in your life. Get the finances split for good, let her know you are keeping the house and tell her to contact your attny with any other questions. You said yourself she does not handle crises well. And while in large part I think the idea of "creating crises" is not as effective as people hope, in your case your W sounds ill equipped to handle much of anything without assistance.
People cling to hope and we ALL need hope, what do we have without it? Hearing a story here and there about people that got back together is nice but it doesn't mean your story will (or won't) end that way.
You are allowing somebody else who seems to have little regard for you run your life. Why?
