The Circumstances of Being Chosen as the Villainess's Favorite

I possessed a low-level supporting character whose only role is to be a foil for the Female Lead.
​I get cursed at and slapped by the Villainess in the Female Lead's stead, and to make matters worse, even my fiancé has fallen head over heels for the Female Lead and become her doormat.
​I can't take it anymore!
​Rather than continuing to live as the Female Lead's lackey,
I'm going to switch sides to the Villainess—the richest and most powerful person in this world!