It's an isekai where the FL gets transmigrated into the villainess's body. The villainess was the one who tortured the ML. During the main story, current timeline, neither tortures the other, it's all in the past.
The FL and ML fall in love.
It's actually a wholesome story about love and forgiveness. Without spoilers I can't really say much else. (there is "angst" and you do see past memories of when the ML was being mistreated)

Villainese beast torture by not my cup tea i hate vilainese FL usualy trashy and lazy writing ..