Ever since Lena Luthor (Katie McGrath) found out her dear friend Kara Danvers (Melissa Benoist) was Supergirl, it felt like there was a bomb waiting to go off. That explosion finally happened in Supergirl's seventh episode, when Lena was forced to confront Kara for her lies and betrayal in the Fortress of Solitude. And boy, was that an emotional showdown.

There were tears, there was screaming, and there was a fair amount of heartbreak on both sides, and we can't help but feel like this divide between them is getting harder and harder to mend. Is there any way to reconcile these two and get back to the beautiful friendship they once had?

TV Guide asked Katie McGrath to weigh in on that very question, as well what it was like to prepare and film that scene with Melissa Benoist that we've all been waiting for. Check out the full interview below!

Discover Your New Favorite Show: Watch This Now!

Katie McGrath and Melissa Benoist, Supergirl

What was it like to film that super emotional scene where Lena finally confronts Kara?

Katie McGrath: Oh, horrendous. It was a long, very emotional day, and if you can see how much Melissa is delivering on her coverage, she gives just as much when the camera's not on her. So, it was like a full day of crying and emotion. That was horrendous. The finished product was glorious, so it was worth it. I mean it's one of these things where you kind of hope that the end is going to be good, but the filming of it at the time — you're just so spent. You're just like emotionally going, "I've got nothing. I'm sorry. There's nothing left." We're just sitting on set, and you literally can't articulate words, because you're just — the thing about things like that is that your mind knows it's fake, but your body doesn't know, because you're asking your body to go through it. So the emotions are all, as far as your body is concerned, very real. And it doesn't matter that your mind is telling you that everything's fine, your body is like, but it — that happened! So yeah, you go home, and you're not a normal human being after it for sure.

Over the course of the season, do you think Lena's had conflicted emotions about deceiving Kara?

McGrath: I think right now a lot of Lena, or all of Lena, in the start of Season 5 is she's running on pure reaction and pure push. There's not a big time jump between Season 4 and Season 5, so what she's doing right now, it's pure hurt. And I don't think in the earlier parts of the season that she's had the ability to self-reflect on herself. She's just on a roll of just trying to make Kara feel what she felt so that she can really understand what that meant to her and the deceptions over and over and over again. I don't know what's coming up because we obviously don't know, but I think as time goes on, it's going to become more and more difficult for Lena to not suddenly start to become self-aware of what it is that she's doing and sort of feed that into the decisions that she makes. Because she does believe she's doing the right thing, but I think it's going to become harder for her to ignore the ramifications of what she's doing.

Everything We Know About the Crisis on Infinite Earths Arrowverse Crossover

Do you think that there is any potential for them to reconcile after all of this deception now on both sides?

McGrath: I think there's always potential, you know? I think the writers are very smart, and I think they have a very clear, articulated plan about what they're doing. And I would hate to think that you're not going to get Kara and Lena back as they were before. And I think fundamentally Lena is still a very good person, and I think she does just miss her friends. She misses Kara desperately, and part of me believes that Lena would do anything to get that back if it meant that Kara wouldn't, as she thought, betray her again. If Lena felt that Kara couldn't betray her again, I think Lena would do anything to get that friendship back. I think the illustration of that is how hurt she was. You couldn't feel that amount of hurt if you didn't actually care.

Katie McGrath, Supergirl

There will obviously be a moment in this week's episode when Lena has to decide how far she's willing to go. Do we think she would ever truly hurt Kara?

McGrath: Oh, you're going to have to watch the whole episode. There are many brilliant moments in the whole episode, so you're going to have to tune in to that one. What I have to say about it is that episode is very exciting. It's like nail-biting. Every episode is slightly different, but this one's sort of like edge-of-your-seat, nail-biting, very tense episode. So, definitely tune in to see what happens.

Switching gears to Hope, I have to say as a sci-fi fan, I have been programmed to think that all forms of AI are eventually going to turn on their creators. Is that something we should be worried about with Hope?

McGrath: Well, I mean Andrea [Brooks] could never be anything other than lovely and wonderful. Have you seen her face? That is a face of pure innocence, Andrea Brooks, which is why she makes such a great AI. I think you're going to, again, wait to see... I have to say I'm very, very lucky in how they decided to use Andrea's character this year and how wonderfully Andrea managed it. Being pregnant, and being on set, and doing long days, she never dropped the ball. She was always wonderful and completely created this character that was so completely different to Eve Tessmacher but still so wonderful. I just was in awe of her. She's a wonderful, wonderful lady.

Lena also finally gets to be part of the big crossover this year. What was it like getting to take part in Crisis?

McGrath: It's been kind of nice because every year I'm never involved, and I've always feel a bit left out because it's always such a huge thing and a big deal and kind of very special because obviously so much of everything leads up to it. And to be involved in it this year I was like, "Oh, I kind of feel like part of the gang." I felt very flattered actually... It is insane what they have managed.

Supergirl airs Sundays at 8/7c on The CW.

Melissa Benoist, Supergirl



(Disclosure: TV Guide is owned by CBS Interactive, a division of CBS Corporation.)