You spent so much time focusing on the fact that your W made this big "to do" about telling you about her stable/modest new job and salary and you went on and on about how she is finally becoming grounded and responsible all for what? Nothing. In the end she did what she wanted to anyhow and once again your expectations went through the roof.
You just made a huge post about how she lacked responsibility and money management when she was earning a higher salary. Yet, you enabled that further when you offered to help her out financially. Again, if her behavior was so unpleasant and damaging WHY did you offer to help her continue it? Want to know why? Because she *finally* needed you for something and in your eyes the *something* was a good thing. She wants to party and blow all her money, well, that is fine. You bitch about it here but when you have the opportunity to show her some consequences to her actions you cave with the hopes she will see how great you are. At the end of the day she did what she wanted to and you were an afterthought.
It is really easy to say money changes people. And sure, sometimes it does but 90K is hardly life altering when you are raising two children in a large metro area. Perhaps you don't want to see the bigger issue but maybe she changed because she was unhappy and wanted a new life and her higher salary gave her a bit of freedom to pursue that life.
This is exactly why I think looking at small positives in your situation is nothing more than false hope. You must start looking at the bigger picture and patterns of behavior then weigh them against the small positives.
I feel, in your eyes, you thought a lower salary for your W would give you some control over the situation that is your marriage. With less money she would be able to do less (partying and being independent) and somehow she would become who YOU want her to be as she could no longer afford to be who she was during your separation.
And that my friend is the big reason you must detach and stop trying to control the situation. As you have learned, at the end of the day your W will do what she wants, when she wants and how she wants and there is not a thing you can do about it.
Don't voice your disdain for her behavior here then turn around and offer to help her continue what you deem as bad or inappropriate behavior though.