I do agree at some point that yes we are gear up for having a sex on this earth on the contrary I also agree with the fact that taking a chance to have a relationship with a married man who can not leave his wife and child/children for you that makes you feel actually cheated and used. The second feeling of being cheated and used is most prevalent after such a relation but at time the momentary happiness gives you strength to live and to struggle in your day to day life. So, do whatever you want to do eventhough you know the facts beforehand but never repent as you have committed some crime but always learn from your past.