I like the support that bizarre gives, however, I have to disagree with her labeling of herself as an "old lady" - 57 is not that old anymore. My W's nearly 68 year old "boyfriend" is indeed an old man! When they first met, he lied and told her he was a youthful 57.
I have a gut feeling that Heather and her H will eventually get back together. It may be long after they are D'd, but I believe that with much time they will find that they were destined for each other.
It is great that Dan and her are good friends now. That is what is best for what is most important - their children.