I'm not sure if I was ever completely OK with it...Several things didn't make sense to me. Time is finite so spending time with another draws from the pool of time either me, kids, job, or other outside activities. Feeling like she spending time, dates, sex out of obligation or fairness. This is not uncommon...really don't care if its completely common I don't want to be around anyone who's forcing themselves to be with me ....no favors please not that hard up. And now the email evidence has bore this out she was doing certain things out of fairness. One of my rules was this need not touch our kids lives ....unfair to them ...wrong age.
The computer is a family one in the family room of our house. Each person has their own user screen with passwords.. My daughter was most likely using it for school or on facebook and my wife was to lazy to log out and relog on under her own user screen jumped on to do god knows what I'm sure she wasn't at that moment sending emails to bf she would have closed it and logged off .... just stupid.