EXCLUSIVE: Morena Baccarin and Ben McKenzie Plan to Marry, Her Ex 'Blindsided' By Relationship

Looks like fans weren't the only ones surprised to find out about Gotham co-stars' Morena Baccarin and Ben McKenzie's real-life romance.

Multiple sources tell ET that Baccarin's ex, Austin Chick, was "shocked" and "blindsided" to find out that the pair's relationship had become more than just professional.

WATCH: Morena Baccarin Faces Her Ex in Court as Pregnancy News Surfaces

"Austin was totally shocked when he found out about the affair," one source says. "Totally blindsided. When Morena left him for Ben, Austin was devastated -- completely shocked."

Now, newly released court documents indicate that Baccarin and McKenzie intend to take their relationship to the next level.

"Today, I am in a new committed relationship," Baccarin wrote in court documents filed by her attorney on Sept. 11. "I am planning to re-marry. Also, I am three-and-a-half months pregnant."

NEWS: Morena Baccarin's Ex Found Out About Her Pregnancy Only a Week Ago

According to eyewitnesses, McKenzie visited Baccarin multiple times on the Vancouver set of her film Deadpool -- which shot between March and May of this year.

"He stayed at her condo," a source tells ET.

Baccarin films Deadpool night scenes on April 1 in Vancouver, Canada.

In court docs, Baccarin claimed that "In March 2015, Austin and I were talking about separating as I told him I thought our marriage was not working and we should possibly divorce."

Chick did file for divorce from his wife of four-and-a-half years on June 12, citing "irreconcilable differences." According to a source, a fan sent Chick a photo of Baccarin and McKenzie together in Vancouver.

"Austin confronted Morena about the photo," the source says. "She didn't deny it and said she no longer wanted to work on [their] marriage."

PHOTO: Morena Baccarin Hides Her Baby Bump on the 'Gotham' Set

Prior to the divorce, in the spring of 2015, Baccarin and Chick had reached an informal agreement regarding custody and visitation of their one-year-old son, Julius, wherein Chick would be provided with a New York apartment and spend considerable time with the child to accommodate Baccarin's eight-month shooting schedule on Gotham.

On Thursday, the former couple faced off in court once again -- on the same day that news of Baccarin's pregnancy went public -- regarding custody of their son.

Get the details on the tense face-off in the video below.

ET has reached out to reps for all three parties for comment.