He certainly wasn't married like YOU thought he was married!!! I believe, if you really think about it, that you knew from the first, deep down, that the relationship between the two of you wasn't quite "right." It was just that you managed to tweak it in your imagination to being something other than it was. So maybe you need to think about what the biggest attraction of having him pay attention to you really was?
Also, you say you've never been in a relationship which was both sexually and emotionally fulfilling. Partly, the kind of relationship DQ described is only possible when we're older, accepting of ourselves, free of neediness, and unafraid to look deep into our desires and to share them fully. (I'm still working on these things, and very happy with my progress!)
Also, since all relationships are 2-sided, you might want to look at your own blocks to emotional intimacy. What was your parents' relationship like? Your childhood? Why did you marry a guy 20 years older than you who wasn't capable of intimacy? What would it look like to be in an emotionally intimate relationship--how would you act differently? If you change yourself, the sorts of people you attract will necessarily change, too.
You wondered if Mr-Not-as-Thought was in an MLC. I've witnessed several first-hand, including my H's, as well as hanging out on the MLC board, and they are extremely painful affairs (pun intended). They are really extended depressive episodes in which the Mid-Lifer grapples with questions of aging and life accomplishments while dealing (for the first time) with severe hurts experienced as a child or teen. People with less damaging childhoods, or who are willing to face their demons, tend not to have them.
The MLCer tends to go through a series of personality changes for several years, from constantly angry, to a teenaged mentality, to withdrawn, etc. While under the influence of the teen brain--well, I think you've had experience raising boys?--they're secretive, have a huge sense of entitlement, and lie and rationalize and compartmentalize and have a rather distorted view of their marriages. Most have emotional or physical affairs, which they rationalize in the most amazing ways. They cause a lot of pain and damage, and yet are agonized and confused throughout.
So, yeah, you'd be well advised to steer clear of this guy, whether he's going through some sort of crisis, or merely a practised philanderer. But don't feel "embarrassed and silly." Like everything else in life, this was a learning experience--there were reasons why this situation developed as it did. If you can figure out what your contribution was, and what you'll do differently next time, then this whole episode hasn't been wasted.
