Darling, Let's Split His Inheritance

She thought she had traded her youth for wealth and prestige, but the first wife gave her love;

They thought they had won with love, but their allies betrayed them;

When all the money fell into his hands and the people from the past took their final bows,

What greeted her was the whisper of the dead and a familiar, eerie smile...

In this deadly game sweeping up wealth, desire, and life, who is the protagonist who was truly switched?