Toward the end of my marriage my home was bizzaro-land, there was a circus going on here while I was at work and I felt I, at least, deserved to know what the hell was going on in my own home.
One of the tenements of Alanon is to not "check up" on the alcoholic, and I agree to a certain extent. IOW, AFTER you pretty well KNOW what is going on, it only serves keep you in pain. But as a fact gathering mission, I believe it has merit.
If you want your eyes open quickly and probably painfully, I would say follow her to the corner store. Whatever you find there will no doubt help with your decision making.
I installed a key logger on our home computer, it was a source of great PAIN, but gave me clarity/insight I'd have gotten no other way. I would STILL be scratching my head wondering about what went on in my home. As painful as the truth was, I'm glad I got it, made my hard decisions much easier.
Good luck in what ever you decide. We have a saying in Alanon, "More will be revealed". Have you considered Alanon?
Thanks and God bless us all,
Coyote