Thanksgiving advice: My mother-in-law did something utterly unforgivable. But my wife still wants her at Thanksgiving.

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Dear Prudence,

A month ago, my wife’s sister “Simone” caught their mother in bed with her husband. Needless to say, Simone is going through a very difficult time in the wake of this double betrayal. The thing is, my wife wants to invite my MIL for Thanksgiving (she’s never really gotten along with her sister and thinks the entire thing is funny). I’m thoroughly disgusted by my MIL’s behavior and don’t want her in our house ever again. How can I convince my wife that what her mother did to Simone was so sleazy it should be a deal breaker in terms of having her around?

—Squicked Spouse

Dear Squicked Spouse,

Let your wife decide. It feels like this is between her, your MIL, and Simone, who was the victim. Keeping it