The PMS murder : a Jaine Austen mystery / Laura Levine.

Enhanced descriptions from Syndetics:

On the front lines of the battle of the bulge, otherwise known as trying on bathing suits in the communal dressing room at Loehmann's, Jaine makes a new friend--a wanna-be actress named Pam--and gets a new job: sprucing up Pam's bare-bones resume. Their feeling of connection is mutual, so Pam invites Jaine to join The PMS Club--a women's support group that meets once a week over guacamole and margaritas to commiserate about love and life. But joining the club proves to be more a curse than a blessing for Jaine. Though she is warned that Rochelle, the hostess, makes a guacamole to die for, Jaine never takes the warning literally. Until another PMS member--Marybeth, a relentlessly perky interior decorator--drops dead over a mouthful of the green stuff after confessing she is having an affair with Rochelle's husband. Turns out that someone knew about Marybeth's nut allergy and added a fatal dose of peanut oil to the dip. While Rochelle and her husband are the obvious suspects, everyone at that night's meeting is under suspicion, including Jaine, putting a new job opportunity at a conservative downtown bank in jeopardy. So, instead of dishing dirt with The PMS Club, Jaine has to dig up dirt on the surviving members--an alcoholic widow, a sassy sixty-something, a too-fabulous honorary male PMS-er, and Pam. As Jaine delves deeper, she tunes into some truly sinister vibes, and it soon becomes clear: someone in this club thinks getting away with murder should be a privilege of membership...