I haven't divorced yet, but unless I am in temporary denial, I know it is coming soon.
The straw for me was also an affair, but a very weird one. She wanted me to be ok with the affair, and thought that I should be. The affair is forgivable, but not if it is not seen as doing something wrong. She told me yesterday that no matter what happens, her will still be her best friend. I am the person who pushes down inside my anger, I was just speechless. But it hit me hard with the realization that she isn't any where near ready for recovery.