On the Feb. 19 episode of Grey's Anatomy, Maggie (Kelly McCreary) drops a bombshell when she accuses Meredith (Ellen Pompeo) of cheating on Derek (Patrick Dempsey). Meanwhile, Bailey's husband Ben (Jason George) gets some shocking news about his little brother, while a new couple forms among the hospital staff.

Did Derek cheat on Meredith while he was in DC?

Kate Walsh joined the medical drama as Derek's wife, bringing up the third angle of the love triangle that Meredith and Derek found themselves in. ... However, their marriage was soon cut short when Derek cheated on her with Meredith.

What episode did Derek cheat on Meredith?

Watch this scene from Grey's Anatomy Season 11, Episode 15: I Feel the Earth Move.