Some people are better at moving on from a breakup than others, but fortunately, few are as bad as the ex-wife in the upcoming thriller "Unforgettable."

A new trailer for the film, released Tuesday, shows Katherine Heigl as Tessa, a woman who can't deal with the fact that her ex-husband, David (Geoff Stults), is moving on. When he gets engaged to Julia (Rosario Dawson), Tessa feels like her life is being taken from her, and that sends her over the edge. Her behavior becomes increasingly alarming, escalating from biting comments to full-on violent behavior.

Tessa is definitely unstable, and she wages her battle against both subtly and blatantly. It gets out of control fast, to the point that she tries to pin a murder on Julia. Since Heigl so often plays sweetheart characters, it's fun to see her take on a darker role. Crazy Town, here we come."Unforgettable" is slated to open on April 21.