The reality of it may hurt but you knew this already in your heart I think.
I don't know what state you live in but where i live infidelity could be part of a divorce filing that is "with cause" If you can prove it and helps in the divorce itself
BUT forget the legalese for a minute. Personally, if I had my d7 visiting with my STBX other guy I would require I know more about it and that the lying stop. I would demand it.... its actually something that in a custody discussion woudl be a big issue. I think its time for you to put the hammer down!
_________________________ Me-48 Spouse-WAW 52 Married for 10 years D7 ILYBNILWY 7/15 Suspect EA/PA 12/15 No confirmation/denial She files 1/2016 Working towards the Big D ...still in progress....