Astonishing (2004)

Mandy receives a DVD on which a mysterious man tells her she's going to lose her husband, her current lifestyle, and her identity. Mandy goes see a shrink, but nothing comes of it. Then one evening she and her husnand Kenny get into an auto accident. Three weeks later Mandy wakes up, and the world has gone topsy-turvy. Kenny's assistant Fiona has usurped her identity as Mandy, and everyone else is recognizing Mandy as Fiona.