Spoiler alert: This post contains details about the final episodes of13 Reasons Why.

WhenKatherine Langford took on the role of Hannah Baker in Netflix’s13 Reasons Why, she knew she would have to go to some dark places. After all, the show tells the story of Hannah Baker’s life, and more specifically, why she decided to commit suicide.

In the show’s 13-episode season, Hannah’s struggle grows, with each designated “reason” for her death only getting more intense. While the beginning of the show focuses on things like high school bullying and friendship gone wrong, the later episodes deal with things like death and rape. And for Langford, the final two episodes presented her with her greatest challenges. “The further you go along, the more involved you become with Hannah and the closer I felt to her. And also the acts that happen are increasingly harsh,” Langford tells EW. “Episodes 12 and 13 made me a little bit nervous because as a young adult playing a young adult, these issues are so relevant.”

The issues she’s speaking about in the final episodes are Hannah’s rape in episode 12 and her suicide in episode 13. “I just wanted them to be told right because I feel so many TV shows and movies that have shown these issues either romanticize them or they use them as a plot device. I wanted this story to be truthful,” Langford continues. “12 was difficult because I put a lot of research into it. I spoke to Rebecca Kaplan fromIt’s On Us and I spoke to a psychiatrist who deals with adolescent development and there was a lot of conversation about why things happen in the way they happen, things like why Hannah doesn’t say no.”

Langford adds: “There was a lot of discussion that went into that about how we were going to shoot it. When we did it, I felt super supported and absolutely comfortable on set, but it was very strange because that act makes me sick to my stomach. It’s so sickening and it’s uncomfortable and it’s ugly, but that’s also why we needed to show it.”

As for Hannah’s suicide, Langford says the acting wasn’t as difficult as the goodbye. “That final scene with Hannah in a bathtub, that was tough and that stuck with me because it was the last day that Hannah lived,” she says. “Playing her for six months, you develop a memory and a history for what she’s gone through and by that point, I felt very close to her and I felt like she was a person. The story is so personal that when it came to that scene, not so much the acting side of it, but more the having to let her go was really difficult.”

13 Reasons Why is available on Netflix now.