This is a movie probably from the 80s, maybe early 90s.
A woman has 2 lives. In one, she is well behaved. The other, a second personality, is wild, violent and cruel.
In once scene, she is caught by another woman while torturing a man in a sado-maso situation.
is it this? https://www.youtube.com/watch?v=-YWKQbfgX8g
Maybe it’s (La double vie de Véronique) 1991