Without You (2011)

Without You is a brand new three-part drama adapted from the novel What to do When Someone Dies by writing duo Nicci Gerrard and Sean French.
It stars Anna Friel in the lead role as school teacher Ellie Manning, a wife who is devastated to learn her husband died in a horrific car accident with a mystery woman in the passenger seat.
Stricken with grief and refusing to believe her husband is having an affair, Ellie sets out to find the truth of who the mystery woman is, and why she was in the car.