For today’s Dear Prudence, Slate‘s advice column, Prudie a.k.a. Emily Yoffe takes on a doozy: A man who carried on a years-long affair with his stepmother and now struggles with how to tell his father. The son, 15 years his stepmother’s junior, began sleeping with her when he was 17 years old, but continued the affair throughout college and beyond. Two years ago, he broke it off; now, as his father prepares to divorce the woman for (unrelated) infidelity, she’s threatening to spill the beans if the son doesn’t help her get what she wants.

Generally, I’m a big Prudie fan. And admittedly, this is a tough nut to crack. But this time, while Prudie’s overall advice—-tell Dad, verrrryyy caaarrrefully—-is on the mark, her specifics get into victim-blaming territory. Quoth Prudie:

Tell your father you have been living with a sickening, shameful secret that has been a blot on your life. Give as brief an account as possible and emphasize that you were a minor when she seduced you. (It would help if you were also a virgin.)

Prudie’s advice plays into an age-old rape excuse: Just replace “but she was a slut” with “but he was a horny 17-year-old boy.” Virgin or no, the 17-year-old was certainly taken advantage of—-and yes, raped—-by his much-older stepmother. That rape resulted in a pattern of fucked-up-edness with a clearly exploitive woman that the man was only recently able to end. Even now, it will almost certainly ruin his relationship with his father. Prudie would do best not to add insult to injury by insinuating the man could only have been coerced into having sex with this woman if he was an entirely inexperienced teen.