I think Vanessa realizes that her Dad took the reality of his diving in a lake to save a gerbil, and turned it into the fiction of him diving in, under fire, to "save" Jim Rassman. Many children of liars first realize their parent's true nature when they hear family stories being transformed and exaggerated and told to others as obvious lies. My heart goes out to Vanessa. I wish her all the best as she begins to understand that her very own father is a complete fraud. One can only imagine how she already feels at having been declared illegitimate by her father's annulment from their mother.
Annulments do not make children illegitimate.