She Devil

She-Devil is a 1989 film starring Roseanne Barr, Meryl Streep, and Ed Begley, Jr., based on the 1986 English novel The Life and Loves of a She-Devil by Fay Weldon.

"The story of the greatest evil known to man... his ex-wife."

Ruth Patchett is a frumpy housewife and mother of two whose accountant husband, Bob, is an opportunist whose affection she is desperate for. He meets romance novelist Mary Fisher at a banquet and makes her a client, becoming very friendly with her in the process... too friendly. After Ruth gets fed up with Bob's infidelity and general poor treatment of her, she schemes and plans her ultimate revenge against him, which ends up to be a long, complicated, and darkly funny process.

It received mixed reviews at the time of release, with criticism mostly going to Roseanne's performance (or the fact that she was cast at all aside Meryl Streep) and deviations from the original story, but presently is somewhat of a cult classic.

Tropes:

Anti Hero/Heroic Sociopath: Ruth.
Batman Gambit: Ruth's revenge is assisted by Bob's continual infidelity and his embezzlement of his own clients. Ruth merely brings Bob's crimes to light, and prevents him from using his lawyer's plan that would ensure a Miscarriage of Justice.
Broken Pedestal: Ruth was a fan of Mary Fisher's work before Bob started sleeping with her.
Best Served Cold: From beginning to end, it likely takes Ruth more than a year to get even with Bob.
Cheek Copy: After manipulating Bob's ex-secretary/lover into breaking into Bob's office, she finds these sort of pictures in his file... and mails them to Mary.
Creator Breakdown: Happens to Mary midway through the story.
Disproportionate Retribution: Played with--adultery doesn't justify the length Ruth goes to ruin Bob's life, but considering his long-time embezzlement of his clients, he genuinely does deserve his stint in prison, and likely would not have ever been found out if not for Ruth.
Full Name Basis: Most characters, especially Ruth, refer to Mary by her full name.
Gold Digger: Bob, a rare male example.
- Olivia Honey, a client of Ruth's agency who eventually becomes Bob's secretary, states in her video interview that her dream is to marry a rich and powerful man.
Hourglass Plot: Ruth effectively switches places with Mary and Bob by the end of the story. This theme is even stronger in the book, where more emphasis is placed on Ruth's envy of Mary and her glamorous life than revenge on Bob.
Ironic Hell (figuratively)
Large Ham: Meryl Streep's performance as Mary Fisher is Grade A.
Missing Mom: As part of her plan, Ruth drops off her children with Bob and Mary and vanishes from their lives until the end.
The Reason You Suck Speech: Bob gives one to Ruth after a disastrous visit with his parents, invoking the movie's title.
Stuff Blowing Up
Rich Bitch: Mary Fisher.
Roaring Rampage of Revenge: The entire plot.
Screw Politeness I'm a Senior: Mary Fisher's mother, once Ruth switches her meds with stimulants.
Unwanted Spouse: According to Bob, it was a Shotgun Wedding.
What Happened to The Mouse: What happened to Nurse Hooper after she and Ruth start the employment agency? She's seen in a commercial advertising the service and that's the last she's mentioned.
Woman Scorned: Ruth, obviously.
Yandere