The real problem with this movie
This is basically a revenge movie told in reverse where the revenge starts before you even know WHY the character is taking revenge or what the "victim" did to deserve it (if he even did anything). That makes it very hard to identify with the avenger, and the revelation at the end obviously makes it very hard to identify with the aveng-ee. If this were some Michael Haneke-type film pointing out how manipulative these kind of films are, that might redeem it a little, but it's not that intelligent. Really, it just doesn't work.
The "villain" is a sadistic, murderous statutory rapist off-screen and the "heroine" is a sadistic, murderous sociopath on-screen. One is no better and no worse than the other. It's like watching two human cockroaches tear at each other for 90 minutes, and it's simply not satisfying, tragic, or cathartic that one eventually gets its head ripped off.
If this movie is trying to make a moral point--and I'm not at all convinced it is--the point seems to be that LUST is bad, but WRATH is good. I don't know, aren't they both considered deadly sins?