Korosaretaku Nakute Akuyaku na Konyakusha wo Medeteitara, Nazeka Dekiai saremashita

The protagonist realizes that she has been reincarnated as Diana, the villainous young lady from an otome game, from a young age. If things continue as they are, she will be killed by her fiancé, Thaddeus, just as the game's scenario dictates! To prevent this from happening, she must cherish Thaddeus and raise him to be a good boy who won't kill her! However, by the time Diana regains her memories of her past life, her relationship with Thaddeus has already deteriorated. Even if she is kind to him, he will still be suspicious of her, and it seems difficult to wipe away his suspicions. But if she fails to appease her fiancé, he will kill her. What will Diana's fate be?! Source: CMOA