Have you read "NOT 'Just' Friends"? It's a very good book for each perspective.. the injured partner, the wayward spouse and the other person. It gives good boundaries on how innocent things can progressively lead to an affair, inappropriate frienships and ways to rebuild either together or alone.
Fault, blame, erosion of a marriage and relationship happens with tiny cuts that build over time leaving to the eruption of a boil, a major zit popping. Ick, uck and pus spew from something that fermented over an extended period. I doubt anyone here is blameless. We all contribute to the dis-ease of the marriage through our own fears, actions or inactions.
Letting go of blame and guilt allows me to focus on what's really important.. the root cause, my goals and how to achieve them.
Dates are dates. You control how much they hurt or help you. Who knows, someday you may view that as the best gift you ever received. I know that the day of my bomb has become a day of new beginnings, a birthday of sorts for waking up to what was real, what was fantasy and what is most important in my life.
