Your sentiments are so familiar. I am terrible at this sometimes too, particularly when he tells me that he really has decided to choose the OW and it feels so final - that's when I go into panic mode and try to argue and lose my cool. Even when I've told myself to not react in advance.
Engaged Aug 2009 Fiancé had doubts Jan 2010 Happily re-engaged July 2012 Discovery of affair July 2014 Separated July 2014 Fiancé is confused about whom to choose Chose the OW Oct 2014