**Obsessed has a weak, overused concept but a fun ending.** I know this movie has terrible reviews, and it's just a rehash of the same story told several times before, but I still enjoyed it. A crazy woman obsesses over Idris Elba and tries to break his life apart so he can be hers. The same plot pops up in multiple other movies and isn't really that compelling, but what makes Obsessed entertaining is the final showdown. Beyoncé, who plays the wife character, gets to brawl with the woman who messed with her family. The film's pacing is hit-and-miss, and the premise is meager, but the…