Here are things I remember about the book I’m trying to locate:

1. The title may have something about killing the husband. If not the title, around the first paragraph, the narrator talks about how she murdered her divorced husband’s new wife.
2. The book is a modern take on the story of the Affair of the Necklace. The wife in the story is a big fan of Marie Antoinette and the story of the necklace.
3. The wife was a waitress, then became the mistress, and then the wife of an older wealthy man. They live in some rich enclave like the Hamptons.
4. The wife is a big contributor to an art gallery. Her husband thinks it’s stupid to make such big donations and threatens not to make good on their most recent promise.
5. The husband has had a heart attack and is not allowed to be too active.
6. The first wife’s friend introduces her to a French woman who’s staying with a friend but doesn’t know anyone in the neighborhood.
7. As a kindness to her friend, the first wife invites the French women (“Frenchie”) over for lunch and she and the husband discover a mutual fondness for backgammon.
8. The wife’s friend warns her to keep an eye on her husband, but she’s convinced he couldn’t fool around if he wanted to.
9. Of course, the wife hears a noise in the pool house, and catches her hubby dying after having sex with Frenchie.
10. The will is read, and the wife is essentially written out of the will. Meanwhile, Frenchie is left everything.
11. Time passes, the wife loses her home and eventually runs out of money, and has to take a job selling carpet. Her rich friends go on with their rich friends and many befriend Frenchie who is throwing money around to social climb her way into society.
12. The wife tries to set up an auction where she will have a friend anonymously bid on a necklace like Marie Antoinette’s that she knows Frenchie covets – to raise the price. But Frenchie doesn’t take the bait, and the wife’s friend is stuck with the necklace that the wife will have to buy from him.
13. The wife – as a last ditch effort – spends the last of her $ to throw a soirée only to find out that Frenchie has scheduled one for the same date and time. When no one shows up at her party, the wife sneaks into Frenchie’s party and pays a waiter to spill the dessert all over Frenchie’s vintage designer dress. The French lady just laughs it off.
14. The wife finds out from a friend who lives in France that French was married and probably drugged and killed her husband who was the wife’s French friend’s son. The friend shows her some sleeping pills that she thinks were used.
15. When she returns to the US, the wife runs into a woman who could be the twin of the French woman. She convinces her to pretend to be the French woman and sign a document giving back everything she inherited back to the wife. The wife is going to drug the French woman and push her off the balcony.
16. The plan works, but it looks like suicide; the French woman leaves info about how she had cancer.
17. The wife gets everything back, pays the lookalike, who is a little ominous about the info she knows and what she could do w/it.

That’s the book.

Thanks for all your help.