I don't see this as a case of greener grass on the other side.
What I see is that the first thing you did to explain the case was talking about college degrees and money. To me it looks like you're having a social inferiority complex. It's pretty clear that in your eyes she was socially "too high" for you - whether you alone thought that or she thought that too is unclear to me, but obviously you thought it was the reason why you were not (good) enough for her.
(what if your lack of money and college wasn't in the slightest the reason she wanted to date other guys?? Ever thought of that?)
I find it very strange that you got married only four months after the separation, to a girl who was pursueing you, which you did barely notice before. To me that sounds like "oh well, if I can't have what I want, let's take what I can get". Not very nice towards your wife.
I don't think you're still in love with your ex. You had no feelings for her in 18 years. How I see the situation is that you discovered that she now is financially/socially not doing as great as you expected - so suddenly you realize that she was not too high for you finally! Hence the confusion.
Isn't it strange that you feel suddenly attracted to her seeing that she has a crappy job and men treating her like crap? Work on your self-esteem issue.
Maybe concentrating on inner values and letting go of your concerns about material status would help?
What are your values? Did you define them clearly? What are your wife's values, this woman's values? Were are you going in your life, where are they going? Such things. Missing money can always be made, but missing values not that easily
my 2 cts. Good luck!
