By now all the denial has to be gone. Elizabeth Edwards has to be fully aware that the father of her two young children is a cad. Maybe he didn't start out that way but that's what he morphed into. The woman he had an affair with is just as shallow, plus seemingly a gold-digger.
There is an older Edwards's child. She is at Harvard Law School. Elizabeth has to know she cannot saddle that young woman with oversight for her brother and sister.
It might be extreme anguish for Elizabeth to speculate what kind of childhood, teenage years, and young adulthood her two young children might have after she dies. She certainly has motivation to stay alive as long as she can. Each day she can build a world of values for her children.