Akuyaku Reijou ni Tensei Shita Haha wa Kosodate Kaikaku wo Itashimasu: Kekkon wa Unzari na node Outaishi Denka wa Seijo-sama ni Sashiagemasu ne

When a mother of three collapses from raising her children alone, she is reincarnated as Olivia, the villainous daughter from her favorite novel, "Twilight LOVE"! Olivia was a clingy duchess who was in love with her fiance, the crown prince. However, Olivia's son is stolen from her by a saint from another world, and her atrocities against the saint are discovered, leading to her execution. In the novel... No, no, no, I'm sick of marriage! I want to save the children more than anything! So why is the crown prince pursuing me...? A romantic fantasy between the incredibly tolerant, child-loving duchess Olivia (the voice actress raised three children!) and the slightly pushy, self-centered, high-spec crown prince (though why does he have the eyes of an abandoned puppy?)! (Source: Kodansha, translated)