Who is Cathy Christopher from The Tears of Autumn and what is their importance?

Paul Christopher's gloomy ex-wife, Cathy is constantly referred to either by Paul or his new girlfriend Molly. Cathy grows hysterical trying to get Paul to write a poem about their lovemaking and punishes him for his inability by taking lovers. Cathy has a perfect face and body. They meet in Europe where she is sent to study languages and art. She is superstitious but void of ideas and wants only to be beautiful. She is sexually insatiable and rapturous but void of skills as a lover and unable to learn. When Paul cannot tell her details of his work as a spy or write her a sonnet, Cathy is upset. When Paul is away, she begins having affairs, first with an Italian actor, who Paul knows and who beats her up when she breaks up with him. When Molly moves in with Paul in Rome, she exorcises Cathy's spirit from the bed.