two steps forward, one step back

I've been divorced for two years, and not being married isn't that bad.  I think I'm coping well on almost every measure.  That said, I am feeling down since the delivery for my ex-husband of a letter from our state's department of revenue, here at the house that I now solely own, almost certainly on the topic of him not paying taxes.  Ugh.  

The letter arrived yesterday.  He was here a few days ago, visiting one of our daughters, and he scoffed when I mentioned my belief that his practice of being paid in cash and not putting money in the bank is related to tax evasion.

I'm not upset that he might be caught.  I am upset with myself, for spending so many years with a person whose values clearly diverged from mine, in significant ways.