Blake Lively and Jenny Slate Break Down Their Emotional It Ends with Us Scene: 'I Had Snot Pouring' (Exclusive)

Note: This story contains spoilers for It Ends With Us, in theaters now.

Blake Lively and Jenny Slate were locked in for their most emotional It Ends With Us scene together.

In the adaptation of Colleen Hoover's book, Lively plays Lily Bloom, a florist who strikes up a friendship with Allysa at the same time she embarks on a toxic relationship with Allysa's brother Ryle (Justin Baldoni, also the director).

Near the end of the film, when Lily tells Allysa about Ryle being abusive and her pregnancy, Slate's character offers support and tells her not to go back to the relationship. The pivotal scene proved to be emotional for the actresses to film.

"You made it so easy. I just watched you," Lively, 36, tells Slate, 42, in an interview with PEOPLE.

Adds Lively, "I was like ... 'I'm not going to be emotional. We've had so much emotion, I'm just going to play it quite stoic.' Then she comes on and I was like— I had snot pouring, full snot! [I was] really trying to hold it in as much as possible."

"For both of us," says Slate, "there was an authentic connection where you know you are a character but you're able to use looking at the other person and really seeing the content of this story that she's telling me is truly taking me apart. I didn't feel that there was any work involved in performing it."

Lively says she "felt so much love and trust and safety and connection with" Slate on set.

Slate, meanwhile, felt nervous: "That's Blake — I don't want to eat it in front of her! I want to do a good job." But, Lively praises the comedian's performance in It Ends With Us.

"[Allysa is] a light character that could very easily, in other hands, have been the person who brings levity or comedy," says Lively, "but the most emotional scene in this entire film and the most emotional performance in this entire film is hers."

She adds that Slate is "somebody who really does it all. We're so lucky to have you in this movie and in real life."

"It's true," Lively tells Slate, adding of her heartfelt monologue scene, "People cheer. In the movie, people cheer when she does what she does."

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About the themes of the film, which come together in this particular scene, Lively says, "Hopefully, seeing a film like this and then having a story like this will remind people that there is a way out. There can be a way out, always."

Additionally, Slate feels "so happy" the characters' supportive friendship shines through in the film.

"It’s one of the driving forces of this project," she says, adding, "Getting to work with Blake and build that bond on this film is something I will always be grateful for. Allysa and Lily have a true bond, human to human, and it’s been such a gift that Blake and I developed that as well. I lucked out."

It Ends With Us is in theaters now.