Maybe I can lend a little perspective (try to read through to the end, it starts off sounding not so great).

I have a Master's and my husband left school in the middle of his bachelor's degree. He's now making more than me because my employment is limited by licensing restrictions and state guidelines. My own perspective is that I put so much time, money, and energy into my degree, that I feel should be making more than him. It was years of difficult pressure and strain to get that small piece of paper, where my husband kind of fell into good employment after slacking off in college. It's almost comically unjust, after what our parents sold to some of us (get a college education! it's the only way to make money!).

I feel as though your wife might have similar thoughts. She's not being fair by dismissing your feelings right now, and I think that's why she's being so defensive instead of understanding of your situation.

Why don't you see what happens if you address that part of the story? You know how hard she worked on it (this doesn't diminish your own immense dedication to your field), she should be making more, based on what everyone says about education. But that was a lie told to us by the last generation to actually see benefits from education. Our generation was the first to encounter issues with having a degree for jobs that no longer are willing to pay us because of the economic decline we're in right now.

I view it differently from your wife. While I sometimes vent about how useless I feel, not making as much while saddling us with crippling debt, I see my husband's success as priority number 1. Since I'm not bringing home the bacon as I should be, we make moves based on his success and what he needs. That's how a relationship should be; you support each other (even if you don't see eye to eye).