I "think" I know why you are asking these questions....you want the pain to stop, faster than slower.
I just went for a long walk to think about your questions....and these are my own personal views (BD being over 14 years ago).
The short answer is no. There is nothing I would change. I made the best decisions that I could at the time, got "advice" as needed from professionals, separated the "business" from my emotions.
Looking back and trying to make any kind of judgement for me of how I handled things would be a waste of time, because I can't change anything.
I still have the same beliefs about the permanency of marriage as I did then.
I made choices and listened to my inner self and what "she" wanted.....I valued my family and that has allowed me to make a place for him in this family which has been good for our daughter and in the long run, with my acceptance that this is how things are, it is comfortable in many ways.
There are some things I found out along the way that I wish I did not know...but not because I ever went searching. Things I would discover accidentally.
I stepped away from him, allowed contact on his terms but did not interfere with his crisis or his life.
Agape and unconditional love for him remain. His crisis is tragic, for him, for me and for our daughter.
We ( he and I ) used to use a phrase about times "no regrets"..and that came to mind..there are no regrets for anything I did or did not do. I am still very clear that if I were the one in crisis, I would very much like to be treated by him the way I have treated him.