You are so right - it is the drinking water! :-) I swear in many of these sitch's that I read, I think they are talking about my W the similarities are so uncanny.
I think you have a very good perspective going regarding the OW. You are right, he is there with you and you are showing him a whole new different side of you and he is responding to that. Keep it up. You will clearly have some days ahead of you that are not great, but don't let those get you down and realize that the progress you are making is real.
My day was good in that out of the blue and completely unexpected, my W called me in the middle of the day to say hello. I was quite surprised, but didn't show it. Just talked positively about common life stuff, i.e. the girls, work, etc. We talked for about 20 minutes and then I ended it by saying I had to get back to work. We both ended with "love you's" so all in all a good convo.
Like you, I will be a better person after all of this is done, regardless of how it turns out. For that alone I am thankful. Here's to more "great" days!