Why does Mary Frazier decide to reveal her secret through letters to her friends and family in the novel, Venus Envy?

Mary Frazier pens letters to her closest friends and family in an effort at closure and honesty at what she believes to be the end of her life. The letters not only contain the confession that Frazier is a lesbian, but are filled alternately with sympathy, love, rancor, hardhitting honest character assessments, and hard-to-take advice.