Dad, One of the things I've thought as I've read through your thread was that your wife may be Bipolar. You really have to find that out before I think any progress can be made. Its scary how alot of the symptons of Bipolar and MLC go hand in hand. I think the main difference is MLC the Walkaway seems to hate their spouse. With Bipolar the Walkaway hates their spouse but they hate themself as well.
I have a Bipolar wife who walked out in Sept 06. She had the affair, got herself 30K in debt, wanted to pull our daughter out of a 5 star school because it wasnt convienient to her new apartment and really just screwed up a pretty damn good life she had for herself. She hit rock bottom when her boyfriend dumped her because she was pregnant, our daughter hated her apartment because it was infested with fleas and bill collectors were calling her everyday threatening legal action.
If your wife is like mine she was so unhappy with things that she knew being without you would make things better...and for a short period of time it did. But now she realizes it wasnt you she was unhappy with, it was herself. The affair and lavish spending were just a bandaid to cover up her real pain. She is unhappier than ever but now has financial problems,has cheated on her husband and broken up her family too. Get her to see a shrink even if you have to without any more handouts to get her to agree with it.