Pity! She's a Whore (1961)

Giovanni holds tender feelings for his sister Annabella, who is pregnant and about to marry Soranzo, although she's not saying he's the father. But Soranzo discovers that his betrothed is deceiving him. When Vasquez, Soranzo's, valet discovers the truth, he helps his master concoct a revenge plot. A big party is announced and Giovanni, his parents, and everyone in the city are invited.