Spoiler alert! This post contains spoilers for the May 2 “Carry Me” episode of Chicago Fire. Don’t read further if you haven’t found the time yet.

Poor Kelly Severide. The brave, kind and extremely attractive lieutenant of Chicago Fire (played by Taylor Kinney) was abandoned by the woman he once loved, and even divorced. Even his innocent soul mate, Shay (Lauren German), makes him sad when she dies in a fire.

Severide’s suffering increases exponentially in Tuesday’s episode, “Carry Me,” when he loses his beloved girlfriend Anna (Charlotte Sullivan) to her recurring cancer.

Sullivan, the Canadian actress of Rookie Blue fame, tells TV Insider about her heartbreaking final scenes with Kinney and her new series, Lifetime’s Mary Kills People.

Sorry to see you go! Are you very famous for playing Tayor Kinney’s girlfriend on Chicago Fire?
Charlotte Sullivan: [Laughs] Every once in a while I get recognized, but with this show, when I cross the Canadian border, when I’m in the airport, people tell me how much they love Chicago Fire! They will ask, “Where is the relationship going? How could you leave Severide?” I had to exclaim: “Those are writers! Don’t be mad at me.” They didn’t know Anna had just received a cancer diagnosis and she knew the clock was ticking.

What was it like working with Taylor?
He’s very realistic, adorable, and normal, and he plays the role very well.
How difficult was it to film their final scene together where Anna dies in front of Severide?
Oh my God! I feel sad even talking about it. It’s terrible. I couldn’t wait for that scene to end; it’s hard to shoot. But the film crew was very supportive of keeping the studio quiet. We had to do some extremely difficult things and Taylor was amazing.

Boy, Severide was miserable on that show!
That’s certainly true. People say: “Never be Severide’s girlfriend. You will die or they will send you away! The writers love to see him suffer.”
Anna seemed to have changed him profoundly.
Well, he had a lot of conquests, and I think he had to go through those things to be able to be with someone like Anna that he wanted to be with for the rest of his life.

Watching his girlfriend die right after he said “I love you” to her in tears would be something Severide would have a hard time getting over, right?
Total. He had never been to such places with his lover before.

That scene definitely requires a tissue box to watch.
It was a great experience for Taylor but I’m glad it’s finally done. I was like, “I need a drink!” So tired, I just want to go home and sleep. I said “Good night, Taylor. See you again.”

Was that the last time you went to the Chicago Fire set?
No, that’s great. Originally, that was supposed to be the last scene we shot, but luckily, there was a terrible snowstorm that ruined my entire shooting schedule so I had to shoot one last fun scene. It was me eating the burger Severide brought me. It was very emotional and heavy so it was nice to end the role with a burger and fries.

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You’re involved with death again in your new project, Lifetime’s new series Mary Kills People, about an ER doctor who stands on the sidelines as a remorseless killer. Your first appearance is in the episode Wednesday, May 14. Who do you play?

I play Nicole, the younger sister of the main character, Dr. Mary Harris (Caroline Dhavernas). They have a serious history together; they could have killed their mother, who was mentally ill. I thought of Thelma and Louise when I read the script.
You definitely have a different look than Nicole.
I had a hand in creating her. It’s rare, but I’ve known the show’s host, Cassie Cameron, for over 10 years. I did Rookie Blue with her. I wanted Nicole to look like a tattooed rockabilly truck driver. The most amazing part of it all is her tattoo. I had a hand in designing them and they are very personal to me. Some were about my family and that helped me get into character.

What attracted you to the role of Mary?
It is a taboo and controversial subject—euthanasia, the right to die with dignity and respect. I respect people who object to religion, but if I were in a situation where I couldn’t shower, couldn’t eat, couldn’t see or hear, I’d want to go. Mary believed this, but she also discovered that there was a lot of money to be made in this business. It’s a gray area that I find interesting.

Does Nicole know about Mary’s other job?
Not at first, but Mary told her in my first episode. Come practice