'i want to tell you something. thank you. these past 5 or 6 months have been very hard. however, had they not happened, i would not have confronted my demons and I wouldn't be the man and father I am now. it took a lot of courage for you to not accept a lesser version of the man you married. I'll be forever grateful to you for it.'
I kinda get where you are coming from...that you would not have improved yourself if not for her actions...but it almost sounds like you thanked her for her being unfaithful to you.