Who is Gina Dinji and Katrin from Lullaby: A Novel and what is their importance?

Gina is Streator's wife..... a beautiful woman whom Streator loved very much. She died shortly after Streator read to her and their daughter, Katrin, the culling song. Unaware of his wife's death, Streator made love to her the next morning. When he learns the truth, he runs away because he is afraid of the humiliation and legal ramifications of his sexual act.