Akuyaku Reijou Route kara Kaihousaremashita! - Game wa Owatta no de, Heroine ni wa Taijou shite Moraimashou ka

A venerable duchess had her ego hijacked by an unknown entity for some time. Lupia's fiancée was taken by the Countess and she was made into a villainess, but she was able to regain her sanity when a voice said, "I will free you from the system. Even if her path to becoming the crown princess is destroyed, she will continue to pursue her own path! Here is the beginning of a fresh start as a villainess!

https://www.cmoa.jp/title/303462/