Who is Zerelda Mimms James from The Assassination of Jesse James by the Coward Robert Ford and what is their importance?

Known as Zee, she's Jesse James' wife. Zee is also Jesse's first cousin and the two play together as children. Zee falls in love with Jesse while tending him after he is shot and almost dies. She becomes engaged to him but nine years pass before they marry. Zee is apparently aware of Jesse's career but insists that he not share details with her. She lives under an alias until Jesse's death in an effort to help him evade capture. She is at home when Jesse is killed and gives in to the questioning by the sheriff, finally admitting their true identities.