Actually, you and I are on the exact same page. Huh.
Okay. Using the employee analogy... as an employer, you put the errant employee on notice. You know as a good boss, that the willingness to step up to the plate now rests solely with the employee. To go in and 'do the work' for them NOW would make you part of the problem, rather than the solution. If they decide to get on board, there will be problems, sure, and you will help them as much as you are able, but the bottom line is, you know what you 'expect,' and are very clear on it... and you MUST know the bottom level of acceptable performance so you know IF they meet the stipulations of improvement within the stated time frame.
This is the same point you are at with your W. You know that you will be okay without her. You'd prefer that it not be that way. SHE knows there is a problem... if she choses to blame you... well... there really isn't anything you can do about that. That's just an excuse.
Now what you have to do is set the 'credible threat.' Very interesting theory has emerged called Game Theory... man won the nobel prize for it. Go look it up. He has done some really interesting work with human behavior and how the mind operates, and how people 'problem solve.' Fascinating, actually. Long story short is... you have to make it crystal clear to your wife that she is on 'notice.' But if you are not willing to walk away, or have not clearly defined what the acceptable bottom level performance is... SHE WILL NOT PERFORM. Period.
If you express your 'credible threat,' she WILL find her way... if she wants to keep the marriage. If she doesn't, she will leave. Neither of these things do you have control over.
Set the boundary. State the case and the consequence and then BACK AWAY. It would be a good idea for you to read Divorce Busting, I think, because there are lots of good things you could implement from that book that won't leave you completely stagnant... feeling like there isn't something 'tangible' you can do.
Long way of saying... you are at the EXACT place where you need to be to save your marriage. Treat your wife as a friend and other person living in your home. Cease all R talk. Put the whole marriage gig on hiatus. You can DO NOTHING until she decides she is going to WORK with you on making your M better. Just like the employee who has been put on notice.
She is CONFUSED. She knows there is a problem, but she is not completely 'geled' on what it is and why it is there. Only until she realizes she has complete control over 'fixing' the problem can you work with her. And she won't realize that until you give her no other option and become a credible threat.
Credible Threats, by the way, are not bad. They are what motivate every single one of us.
Read about Game Theory. Read Divorce Busting. I think once you do those two things, you will be very, very clear on what you need to do and how you will do it. Please let me know...!!