Hi peace- Your clarity and self control show how much you have grown. beginnersmind is right, you are so special and you deserve someone who appreciates you to the fulliest. Don't ever settle for less than that. At least this flirtation has helped you move forward and has shown you that there are possibilities out there.
I am glad your XH is expressing more interest in the kids. They need him in their lives...and not just for a few hours a week. I hope he continues to take more interest.
