If your wife is lying to you, then it is a far more serious issue than even an affair. After all, if she handles the $$ and you are near bankruptcy but she isn't telling you, that's kinda bad too, eh?
Get thee back to counseling. Drag her along if you must. The therapist's job (and he or she can explain that) is, like I said, to be impartial and listen but not to pass judgment.
And you need to figure out whether you can live with the lying, whether or not there really is something going on.