only serious sit downs was about 10 ys ago, thought we got past it
thinking back her behaviors started changing about middle of last yr. for the worst but she has always hidden spending from me and the new lower neck line started about 6 months ago.
I'd be willing to bet anything that her contact with OM began the middle of last year. I would look deeper into intel (cellphone records, credit/debit card charges, etc.) around that time for your answers.
A spouse not even been willing to TRY is almost always an indication of infidelity, in my experience. Then when they tell you "I've been unhappy for a long time," it's just classic "re-writing of marital history" that is standard affair SCRIPT.
I'm not saying you don't have a role to play in the marital dysfunction -- it sounds like you do -- I'm just saying that her refusal to even TRY at this point is more than likely being driven by her interest in someone else.