Oh honey. She must be that blind in love to blame a mistress instead of seeing its the person's fault for cheating.
More so that the worker allowed bribery to let her know the information.
I guess She did say it was a part time worker as opposed to a doctor but other than a phone number for some follow up I'd think the access would be too easy versus them having a receptionist like mail them something in case they forgot something at the clinic too
And, it tends to be common even irl where ppl blame the "homewrecker" than the married person save for the few anecdotes where they didn't know and then sent screen shots to their wives and such
Dunno how much Shiba-san knows about the sugar daddy part of the revenge but Sumire and Mirai can vouch that Karin was hitting on him and not actually caring about Kippei or if she's had other recordings of their phone calls
Is there a normal woman in this manga? That's a crazy stalker level. And illegal as hell.
Despite the red herring of Kise san does some reason having a cunning smile I assume she and the other married woman Kippei suspected was normal
Tho makes me wonder what Karin's parents were like considering the way she still acts in adulthood