When is Adultery or Fornication Committed‪?‬

I never intended to write this tract.  It came upon me as a result of my daily meditation, heart-search and communion with God.  That day, the 16th of November, 1989 I was meditating from Luke 18:20 where the Lord said to the Jewish ruler, 
"You know the commandments: Do not commit adultery, Do not kill, Do not steal, Do not bear false witness, Honour your father and mother." 
I decided to spend one meditation period of two hours in examining my heart and life before the Lord on each of the commandments that was given by the Lord in the above passage.  I will just write out what I wrote in my meditation book that day as adultery.  I believe most of it will apply to fornication.