'Grey's Anatomy' season 13 spoilers: Ellen Pompeo's directorial debut to be heartbreaking

The March 30 episode of "Grey's Anatomy" will be Ellen Pompeo's directorial debut, and the actor has already given the warning that it will be a tearjerker.

"I couldn't wait to make everybody cry," she said during the PaleyFest panel for the show.

The episode will see the health of Diane (LaTanya Richardson Jackson), Maggie's (Kelly McCreary) adoptive mother, deteriorate, with the doctors struggling to discover how to treat her. In episode 13, they discovered that she has inflammatory breast cancer. The problem is that Diane has an uneasy relationship with Maggie, with the latter thinking that the former is meddling with her life. Their argument resulted in Diane leaving without telling her daughter about her condition.

She finally reveals that she is sick with cancer on the March 23 episode, titled, "Till I Hear From You." The revelation came after her denial that she was getting reconstructive surgery after her breasts were removed. Her claim that she was getting these augmented only pushed Maggie further away from her, because her daughter could not believe that her adoptive mother was getting her breasts enhanced in her old age. After she found out the truth, she took Diane's charts and discovered that the cancer is spreading all over her body.

Given that one of the rumors going around is that a death will be featured in this episode, Diane is the likely candidate to meet her demise. Will she and Maggie reconcile before she dies?

The episode will also show Richard Webber (James Pickens, Jr.) and Miranda Bailey (Chandra Wilson) reconcile after clashing over the issue about the Residency Program.

Pompeo is the lead actor of "Grey's Anatomy," and she has been part of the show since the beginning. She will be the third from the cast who will direct an episode, following Kevin McKidd and Chandra Wilson. Pompeo said that it was the show's director and producer who convinced her to go behind the camera.

She also said: "I've been doing this show for 13 seasons, so I wasn't really nervous about any of the scenes, not to sound arrogant. I was more nervous about the technical aspects... I have the best cast in the world to work with."

Episode 18, titled "Be Still, My Soul," will air on March 30, Thursday, at 8 p.m. on ABC.