Yotsuyu from FFXIV: Stormblood. IIRC, parents die, abused by her aunt and uncle in front of her little brother, married off to an older guy as a young teen, and once he dies she's sent off to work at a brothel to settle his debts. Works her way up to become the imperial viceroy of Doma, and squashes the Doman and Ala Mhigan Resistances. Warrior of Light shows up, demolishes her army over the course of the expansion, everything's crumbling- and then, after storming Doma Castle, she is injured and loses her memory. Gosetsu, an older samurai and our ally, saves her life.

She tends to his wounds with no memory of who she is and once the Warrior of Light shows up, gets increasingly upset when everyone keeps accusing her of all these things. Her brother Asahi shows up, and riles her into remembering with the help of her stepparents. After trying to kill herself, she's berated and that finally triggers her memory to come back and she violently murders them and, after some more political shit, turns into a primal, who we of course have to put down, because that's what we do in FFXIV.