As for the once a cheater, always a cheater, I believe that cheating is a choice that indicates selfishness and lack of maturity. You always have the choice to get stay faithful to your spouse or to jump on the first willing partner.
Maybe some people cheat and realize how badly it destroyed their lives, and then they understand how destructive it is and never do it again. But I think a lot of people who cheat probably are able to justify why they did it and so never really do the work to change their behavior and not cheat again.
Cheaters suck.
T 10 years, M 4 years, both 28 years old 7/3/2013 - W wanted D, we attempted to reconcile 7/20/2013 - discovered W's EA, attempted to reconcile 8/24/2013 - W told me she wanted D, filed papers
