the Husband's Secret by Liane Moriarity

Cecilia accidentally discovers a letter written by her husband.  On the outside it says, "To be opened after my death". He is very much alive but away on a business trip.  On the phone, she kids about finding the letter.  "Don't open it," he says.  Channeling Pandora, she opens it anyway changing everything she knows about her life.  The truth can be a dangerous thing.  Is it better to live with a lie or suffer the consequences of the truth?  And here is another question.  If the primary characters in a novel are mostly women and the issue is fraught with emotion and personal consequences, is it always classified as "chic lit"?