It may sound like I'm jumping to conclusions, but your situation sounded a lot like mine. I belive your spouse is involved with another person.
* That explains his coldness and unwillingness to work on marriage. (My ex did same). * Delusions that post D we would be "friends" and still have "dates" and she would come over and "help" with the kids. (At the time she dropped the bomb and was moving out, the last thing I wanted to see was my ex coming over and helping out). * Disbelief when you cut him off financially. Again, living in a delusional world that defies the laws of simple economics. (Self centered).
I could go on. You may want to read about midlife crisis, too. It may help you in devising a strategy to detatch, and protect your heart and finances while he goes through this transformation. You sound like you are doing all the right things to protect yourself. From what I've read about midlife transformation, those who handle it well using it as a growing experience. Others destroy everything they've built.
Lastly, the one of your e-mail is thoughtful and strong. Emotionally, my D was by far the emotionally difficult time in my life.