No lions during this week's episode of Grey's Anatomy (Season 8, Episode 19: “Support System”), but claws and teeth are definitely bared as Cristina (Sandra Oh) rips into Owen (Kevin McKidd) for cheating on her. (And we say, go Cristina, go!) But more on that later. We've got some lesser drama to cover first.

All hail Chief Mark (Eric Dane)! Yes, McSteamy is now steering the ship as acting Chief of Surgery while Owen is home with Cristina, both of whom have "the flu." But Mark is taking the power to heart, and he's sort of a dictator! For example, a teen has a fused jawbone and some other bones that ain't budging neither, and Derek (Patrick Dempsey) thinks operating on the kid is too risky, but Mark commands him to "rise" above the obstacles. So Derek proposes immobilizing the kids head with foam, but Mark thinks that idea isn't good enough commands him to "rise" some more. So Derek has the bright and shiny idea to use a beanbag to prop up the head. And the kid is fine. Surprise surprise.

The other patient this week is an elderly gent named Neil, but we're tempted to call him Old Yeller because he is rocking a serious shade of saffron. Turns out that jaundice is due to a failed liver; and the bloke also needs a new stomach, pancreas, small intestine, and large intestine. A cadaver arrives with all the requisite organs, but Mark puts the kibosh on the transplant when the docs spot a tumor on the donor liver. Richard (James Pickens Jr.), however, goes around Mark's back and sneaks in the transplant anyway. When Mark storms into the OR all a-fluster, Richard shows him that the tumor is benign and orders him to stand down. Mark does, Richard finishes the operation, and Neil comes back to the land of the living boasting a nice, fleshy peach hue.

The boards are looming large, and all the residents are flashcard-ing every chance they can get. April (Sarah Drew) and Alex (Justin Chambers) even force Lexie (Chyler Leigh) to use her photographic memory to absorb medical case files and then quiz them on it. Meredith (Ellen Pompeo), however, has been studying with Callie (who looks awesome in her black jacket, bee-tee-dubs) and bequeaths the so-called Torres Method to her fellow residents at a study sesh at her house.

Teddy (Kim Raver) giddily proposes having a ladies' night with Callie (Sara Ramirez) and Arizona (Jessica Capshaw), and they bring aboard Bailey (Chandra Wilson) to diffuse any third-wheel awkwardness. But Ben has other plans for Bailey which we can't publish here, and Callie and Arizona also want some private time. Eventually, however, they come to their senses, realize that overly-social Teddy is better than sad-mopey Teddy, and meet up with her for dinner. (But Bailey practically has a conniption when she sees that Teddy has brought along not one but two DVDs.)

But all of this just interrupts the real substance of the episode, which is the slow-motion implosion of Cristina and Owen's marriage. Cristina demands that Owen tell her every detail of his affair. Turns out, he was really drunk the night that he and Cristina had their last therapy session, got wooed by a chick at a bar, and slept with her. Cristina cries, realizing that Owen wanted to hurt her back after she hurt him by getting the abortion. Owen packs his stuff and leaves, but not before telling Cristina that he's the love of her life and that he'll never love anyone else. He couldn't have told her that, oh, say, three months ago?

Meredith knows the real reason Cristina and Owen are skipping work, but she tells Derek that she doesn't want to talk to Cristina about it since she isn't supposed to know about Owen's crime. But eventually, she just calls Cristina and offers to stay on the line for as long as Cristina needs. And by the end of the episode, Cristina joins Mer's study group.

Is this the dawn of a new Owen-less era for Cristina? Will they work it out, or will Owen join Burke in Ex-land? Time will tell, Grey's fans... stay tuned.

Catch a new episode of Grey’s Anatomy on Thursday, April 19 at 9 p.m. ET/PT on ABC.

Satisfy your Grey’s Anatomy addiction: Like us on Facebook and Follow us on Twitter and Tumblr.