The Girl Next Door (2017)

Si-yeon, who was once a star in the adult entertainment world, is now living as an ordinary housewife, hiding her past. One day, she unexpectedly runs into Ho-gyoo, a former client from her past, and begins to blackmail her, threatening to expose her past unless she complies with his demands for money and physical favors. In an attempt to confront him, Si-yeon starts following Ho-gyoo and witnesses him having an affair with Hee-soo, the wife of the photographer next door, Seung-gil.