For more than a season, "Grey's Anatomy" has been building up to a dreaded reunion, and now it is finally upon us. And yes, it's going to be rough.

In tonight's episode -- fittingly titled "1-800-799-7233," as it's the number for the National Domestic Violence Hotline -- Jo (Camilla Luddington) is going to come face-to-face with Paul (Matthew Morrison), her abusive ex who is still legally her husband. Needless to say, it's going to be unpleasant. Camilla Luddington discussed what's to come with EW and she highlighted that Jo will be "absolutely horrified that [Paul] has infiltrated her world."

The actress revealed that we'll see their run-in pick up where it left off, with Jo being blindsided outside of an elevator, leaving her understandably frozen in fear. Kevin McKidd, who not only plays Owen but directed the mid-season finale, highlighted how important that scene was during a recent interview with Access Hollywood.

"[The] look on her face just told the whole story," he said.

Luddington further explained Jo's reaction, telling EW that, in that moment, Jo "feels like everything is completely turned upside down." To handle that awful surprise, the doctor will try to "get ahead of the situation," because she knows how dangerous and manipulative her ex can be. Unfortunately, Paul will live up to her worst expectations. Luddington shared that "he will attempt to manipulate everyone around her."

"He intends to always undermine her," the actress said. "For Jo, that's terrifying, because she finally has this life that she's built herself that he then may come and destroy again."

Needless to say, Paul's appearance will play into the story, big-time. McKidd shared that the upcoming two episodes will be "very intense" for Jo as she "goes through a huge journey."

We'll see it when the second half of "Grey's Anatomy" Season 14 premieres tonight, Jan. 18 at 8 p.m. ET/PT on ABC.