The Monster Inside the Betrayed Wife summary: Anything that hurts Reina— the “me” inside Reina will never, ever forgive. Full-time housewife Reina is carrying the long‑awaited child of her husband Kenta, and dreams of building a happy family. But then she discovers that Kenta is having an affair with Yuna, the sister‑in‑law who has bullied Reina since childhood. On top of that, she suffers a miscarriage, and Reina’s heart completely shatters. As she is about to throw her life away, whispering, “I’ll come join you too, my baby…,” another personality inside her—Rei—awakens for the first time in a long while. To save Reina, the friend who created her, Rei begins a stand‑in revenge campaign that will not end until every enemy is dragged down into hell.