One important note here: do NOT, under ANY CIRCUMSTANCES, reveal to your husband your source of intel!!
It can work to your strong advantage that he doesn't know what you know, and he doesn't know what you DON'T know . . . ya know??? If/when you decide to confront him, a blanket "Oh, I know all about you and ________ . How incredibly disrespectful to me, to our marriage and to our family."
Think about that for a few minutes: he knows that you know, but he doesn't know WHAT you know. It's a distinct moment of power, in an often powerless situation.
Puppy
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712