Kristen Stewart and Robert Pattinson shot to stardom when they starred in the "Twilight" films together. It was reported that somewhere between the second and third installments of the series, they started a romantic relationship and became one of the most popular reel and real life couples in Hollywood. But the pair broke up in 2013, and now, the actress is finally opening up about how she felt when they decided to go their separate ways. 

Stewart is making the rounds promoting her film "Equals," which stars Nicholas Hoult as her love interest. The film is set in a dystopian world where emotions are wiped out. When Hoult's character, Silas, falls in love with Nia (Stewart), they are forced to go on the run as people who start showing emotions are killed. 

Because the film is also about first love, Stewart said that she could relate to her character, telling The Hollywood Reporter that she drew from her relationship with Pattinson for the role. 

"One of the reasons I was so intimidated by this movie is because I was like, 'This is gonna hurt. I don't want to think about all that.'" Stewart said. 

While she has now moved on from her failed relationship with Pattinson, the actress said that at the time they started filming "Equals," it was hard for both her and Hoult as both of them had just gotten out of their respective relationships. The Daily Beast reports that when filming for "Equals" began in August 2014, Stewart was fresh from her breakup with Pattinson while Hoult just ended a relationship with Jennifer Lawrence. 

"It was incredibly painful," said Stewart to The Daily Beast of her breakup with the "Harry Potter" actor. But the actress said that she was able to draw on her experience as everything that she and Hoult did on the film was "explorative, and a meditation on what we already know." 

Stewart revealed to THR that at certain points during filming, some of the things that she and Hoult would do on some scenes would hit too close to home. 

"We made the movie a year ago. We're still very close to our first loves … It's a painful movie to make in every way," she explained. 

She added that after filming especially difficult scenes, she and Hoult would spend time to bond over their pain. 

"We would go home and be like, 'We seriously need a drink. Let's just stop thinking about everything. Let's not talk. Let's just walk,'" she said.