The Maniacs are Obsessed With the Fake

A cross-dressing duke in a BL novel who pretends to be an obsessive maniac. That was a perfect sentence to describe her.
Levin de Bervein was the lord of a prestigious duchy and a renowned swordmaster with outstanding looks. While seemingly perfect, he harbored a secret: he was actually a woman! After falling into water unexpectedly, she met the eccentric princess. Sister, please become a fake obsessive maniac! Since they were inside this tragic BL novel, the princess wanted her to seduce the bottom male lead instead of the original storys obsessive maniac to prevent the worlds destruction. She followed the plan and seduced him, acting like an obsessive maniac. However Act like you love me. If you dont, I might just kill the person you love. The bottom male lead, whom she manipulated and discarded, returned as the Emperor of a new empire. What do I need to do to have you? War? Massacre? The original Obsessive Maniac 1, the enemy empires emperor, was truly insane. With just one kiss from you, I can dedicate everything I have. This heart, this empire. The childhood friend whom she thought was innocent turned out to be the real Obsessive Maniac 2 from the original story. For some reason, the obsessive maniacs from the story all come after her.