We took our time and talked about infidelity before we got married. H knew the lines as his former wife cheated on him which is why he said he had the A... He was not the type of man that I thought was capable of cheating.
Neither was my WAW. In fact, while we were dating she had spoke about a past boyfriend who cheated on her and the effect it had on her.
But what happens is that they become emotionally involved, and issues of it being satisfying and wanted are prioritized and justified in their minds over issues of right or wrong. It's called a "slippery slope" because they get caught up in it and once their hearts are involved it's difficult for them to say no. People who had once been cheated on and know the devastation and pain find themselves being the cheater, People that never would've imagined cheating end up cheating. No one's perfect and only when and if the time comes do we really know what we'd do. Same holds true for the LBS. How many spouses at the beginning of their marriage would say "if my spouse ever cheated on me, I'd divorce him/her", but then when it happens, they fight to save the marriage instead of divorcing.
So it sounds like to me that you're holding onto that he betrayed you, and it serves up righteous indignation, which helps fuel the anger and resentment I wrote about. There's a saying, "You cam be happy, or you can be right". Again, as long as you hold onto that, you can't move forward.