I'm very sorry for what you've gone through. I think you've come to the right place, though. There's a lot of information here about MLC. You might want to start with "Midlife for Dummies," a humorous (but incredibly accurate) template for what the MLCer must do to mess with his spouse's mind. I believe your H has, indeed, managed to get out whole chunks of the "script" and acquitted himself in a textbook manner!
From what you describe, it does sound like an MLC. But then, an MLC is really just a period of deep depression, so he's also exhibiting many depresssive signs. Do you know if there was some sort of trigger in 2006--something to do with his abusive father perhaps, or the death of someone close to him, or some other major life event?
You ask about the anger stage. In my experience, the first stage (denial) was a time of the MLCer closing off emotionally, denying he had emotions even. "I don't know" became the answer to just about every question. This was a very passive-agressive period, in which he would block everything until I became upset or angry, and then quietly state, "I can't talk to you if you're crying/yelling."
After that, everything made him angry (but nothing was his fault). His boss and co-workers were stupid. The news was aggravating. The neighbours. Other drivers. His family. MY family. And how could he not get upset if I did something that annoyed him? At this point, the MLCer often demonstrates a nasty streak that comes as a bit of a surprise. It's like an outward manifestation of the nasty voice they hear internally, telling them they're no good, etc.
You ask why someone who was depressed or confused would move in immediately with another person. It's for the same reason they try to bury themselves in golf, snowboarding, alcohol, etc--the "high" of being with someone new, like the adrenaline rush of snowboarding or the mellowing influence of alcohol, makes them temporarily feel happy. It allows them to postpone doing the hard work of actually dealing with their depression that gnaws away at them for years until they finally face it. Also, having an OP allows them to tell themselves that every problem they ever had was the spouse's fault, and their lives will be wonderful now. It doesn't last, of course, but they create a sort of self-brainwashing state (known as "the fog") which rewrites the past and creates wonderful promises for the future.
I hope that (partly) answers some of your questions. There's a lot of information here, and suggestions for good books you could read to help you understand why your life has been upended, and how you can move on.
