Katherine Heigl on Obsessive Relationships and Finally Getting to Play a Villain

Suffice it to say that Unforgettable more than lives up to its title. The thriller, in theaters April 21, stars Rosario Dawson as Julia, a domestic violence survivor who meets the man of her dreams (Geoff Stults). But as she gets closer to him, Julia learns that her perfect beau has the overly attached ex-wife from hell: Tessa (Katherine Heigl), who quickly sets out to destroy their budding romance.

As manipulative, sociopathic Tessa, Heigl steals every scene she’s in, making the film a ludicrous good time. After a long career playing heroines and good girls in romantic comedies like 27 Dresses and Life As We Know It as well as on network dramas like Grey’s Anatomy and State of Affairs, here Heigl proves herself a wildly entertaining villain all the way up through the film’s grisly final showdown.

In conversation with TIME, Heigl opened up about the pressure on women to be perfect, obsessive relationships and going head-to-head with Rosario Dawson.

TIME: What a movie! How did you first encounter the material?

Katherine Heigl: It was sent to me and Denise di Novi—who I had worked with years ago on Life As We Know It as a producer—called to say, “Hey, I’m directing this. How do you feel about the role and do you think you could even do it, Katie?” Which was like, “Um, yes! How dare you challenge me?” I was pretty excited that she even wondered if I could. Then we had a lengthy conversation about how I saw her, and how I’d want to play her, and what beats were really important to me.

So how did you see it?

To me, it was very important that Tessa be sympathetic. That you, as an audience member, have some compassion for her. Not that that excuses her behavior, but it informs some of it, so you understand a little better why she’s making these decisions.

Psychologically, it seems like Tessa’s dysfunctional relationship with her mother looms large in the story.

That’s definitely what made Tessa who she is, and also, Tessa’s suffering from some mental illness that has never been addressed, and her mother is definitely exacerbating that with the pressure she’s put on her—the judgment, the vague disdain for her failings—and the more that pressure builds, the more Tessa crumbles.

I also saw it as a commentary on how women feel pressure to be perfect, which is maybe something that’s passed down from one generation to the next.

Absolutely. I can’t blame my mother for that—she never made me feel like I had to be perfect—so I don’t know if it’s society, or just some inner drive or ambition, but yeah, I know a lot of women like that. I have a lot of friends like that. We keep asking, what is this about? Why do we keep doing this to ourselves? We know it’s a problem. But it’s hard to stop for some reason. The older I get, the clearer it becomes, and the more able I am to cut that shit out.

Your character also has so much of her identity wrapped up in her attachment to this idea of the perfect guy.

Yes, the identity you create from being loved by a man like that. Oh, if he loves me and values me, then I must be of value. I’ve fallen into that trap myself with my husband: I would say, “Well, Josh Kelley loves me, and if he loves me, then I know I’m OK.” But then it’s like, do you love you? Do you care about who you are? Why is it just how he feels about you? You don’t even realize you’re doing it. To be fair: Josh is such a good person with such integrity and such a decent guy that that’s where I was coming from—if someone with that much integrity and kindness thinks I’m great, then I must be doing pretty well.

With a film like this, how do you thread the needle between making it fun and exhilarating while treating serious subject matter like partner violence and mental illness with respect?

You’d have to ask Rosario about the abuse, because she had to dive into that. As far as the mental illness goes, Tessa has no idea that she has a mental illness. This is her normal. She doesn’t think, “I need help,” because she doesn’t have that kind of self-awareness. So she got to be at that computer, which is where you as a performer get to say, “Come on, audience. Come with me and let’s have some fun.”

That scene—where Tessa vapes, drinks wine and masturbates while sitting at her computer catfishing someone—really took my breath away.

Like, have fun with me, audience! Cause I’m having fun! Because if she had any real understanding that she was unwell, she wouldn’t be doing those things. But she was enjoying it. It’s a total dive into her basest nature.

Have you ever felt obsessive about a partner’s ex? It’s such a human thing to meet someone and wonder who’s lurking in their recent history.

And doesn’t it inform you in a weird way about your partner? Like, oh, that’s your ex? Who are you? That’s your type? I’ve never had to deal with anybody’s ex in a way that made me uncomfortable, but I have been in obsessive relationships where it’s just not healthy and there’s no freedom in it. It’s become too controlling and too involved, down to, like, if you won’t tell me what you’re dreaming at night you must not trust me. At a certain point I need to be able to have a dream or two at night that I don’t share with you.

Do you enjoy playing a villain instead of a heroine?

Of course. She was so complicated for me in a way that was so different than a lot of characters I’ve played. I keep thinking of Jane in 27 Dresses—I loved that character—but she was complicated in a very obviously perfectionist way. That’s a relatable, typical flaw. Tessa has a million monsters in her closet so it’s so juicy and fascinating to dive into that. That’s what I like about performing is understanding all different kinds of psychologies and life experiences.

There’s a lot of conversation now about female directors—had you worked with many before?

I work with female directors quite a bit, and I love it. I love women, I love working with women, and I love being bossed around by women. But I also have had extraordinary experiences working with male directors, so it’s more about working with talented, passionate people. I don’t really care what your gender is.

What was your dynamic like with Rosario, especially having to beat each other up on set?

She’s such a badass. She’s super athletic, and I’m not—I’m such a couch potato. It’s pathetic! But she was great in that stuff because she’s careful and she knows what she’s doing. We also had an amazing stunt doubles that really got into the nitty-gritty, because I’ll get hurt. I’ll twist an ankle—it’s just who I am! But we had a lot of fun and I’m not really a method actor so I don’t carry the vibe around with me. She’s really an open, available, gregarious wonderful gal and I felt really comfortable and safe with her—I knew that I could just go there and she would support me. I hope she knew that too.