Sympathy For Lady Vengeance
I remember asking my sister if she'd seen Ek Hasina Thi, and she said, "no", and asked me what it was about. After I gave her a short synopsis, she said, "So it's a bit like Sympathy For Lady Vengeance then?"
I froze for a moment a realised that they do share a similar premise - A female protagonist is sent to prison for a crime she didn't commit. Once out she takes revenge on the man/partner who put her there. The men even eventually get tied up in both films! Though that might be where the similarities end.
Lady Vengeance was released a year after Ek Hasina, though I'm not trying to say that Chan Wook Park made a copy of this! Basically if you liked Ek Hasina Thi (or your female revenge stories), and you want some more, then hopefuly you'll enjoy Lady Vengeance.