I would have to check the email I sent about 2 weeks after the BD. I don't know if I explicitly apologized, but I did acknowledge what I felt to be her issues with me and my behavior and said I was working on them. That email was well received, but it was before things turned ugly.
Just checked, and most of the email was explaining why/how I was behaving the way I was, but I did say "[wife's name], I am so, so sorry for [primary issue in our relationship]." I guess that will have to be enough.
