Read Demon President's Second First Love Manga:
On the night before the heir’s wedding, an infamous woman, who was a love child (born out of wedlock), slept with him! Everyone waited to see how she’d die (or be punished), but she ended up appearing at the civil affairs bureau with the heir and successfully tore apart the perfect couple in Southville. The rumored mistress acted as if she was innocent. ‘I only wanted to more.. sleep with him though?