[Warning: The following contains spoilers for "Josh's Ex-Girlfriend Is Crazy." Read at your own risk!]

If you'd thought you'd seen it all on Crazy Ex-Girlfriend, you were sadly mistaken. During Friday's episode, "Josh's Ex-Girlfriend Is Crazy," Rebecca Bunch (Rachel Bloom) officially hit rock bottom when she had sex with Greg's (Santino Fontana) dad.

After Paula (Donna Lynne Champlin), Heather (Vella Lovell), Darryl (Pete Gardner) and Valencia (Gabrielle Ruiz) tell Rebecca that they know all about her past, Rebecca goes into hiding, convinced that everyone in her life has been conspiring with Josh (Vincent Rodriguez III) against her. She then decides to go full Erika Christensen in Swimfan, a plan which obviously backfires, leading Josh to tell Rebecca that if she ever approaches him again, he won't hesitate to call the cops.

Unsure of who she is without Josh in her life, Rebecca seeks solace at one of Greg's old haunts, and when Greg butt-dials her, she thinks it's fate, but he never becomes aware she's even on the line. Rebecca's mood only worsens when she sees Greg's dad Marco (Robin Thomas) across the bar, and he reveals that Greg is sober, in love and happier than he's ever been — news which only emphasizes the gap between the happy life Rebecca wishes she had and the one she's currently living. So with seemingly nothing left to lose, Rebecca sleeps with Greg's dad, only to wake up filled with enough regret, shame and self-loathing that when her mother Naomi (Tovah Feldshuh) calls, Rebecca agrees to go home to Westchester.

So where does Rebecca go from here? TV Guide spoke with Crazy Ex-Girlfriend's showrunner Aline Brosh McKenna about Rebecca's shocking rock bottom and what's next for our troubled heroine now that she's run out of stories to tell.

Rebecca really did hit rock bottom this week. How did you determine that sleeping with Greg's dad would be that low point for her?

Aline Brosh McKenna: I mean, it's pretty bad. It's terrible. It's kind of the worst thing you could do, one of the worst things she could do, probably. I have to say that Rachel pitched it as kind of a joke one day because she did those scenes with Marco in an earlier episode and they actually seemed to have a funny banter. And so we started joking about it and then after a while it really seemed like in that moment, when she's longing for connection and gets the butt-dial from Greg, where it feels like she's looking for meaning and she's looking for a narrative and she's looking for a story to prop her up that she can tell herself, and she's looking for some way that this is going to make sense. So even though this is something that on the face of it, she would know it's a bad idea, it seems like something that might fit in dramatically in her life, narratively in her life. And that's really what she does, she's a person who tries to tell herself stories, and she's kind of out of stories. It's the last one that she grabs at and that's what the song [with Josh Groban] is about. The song is very much about how we try and tell ourselves a story about our life that makes sense, to not feel futility, to not feel our mortality.

So yeah, it's a terrible idea. Also, she has a tendency to act out sexually, which is something we've seen numerous times in the show. So more and more, this felt like this was the way she was finally going to bottom out. And when that happens, that's why that song is called "The End of the Movie." That's for her [asking], "What do I do now? What comes after this?" And what comes after this for her is kind of coming full circle and going back to where she came from.

We've seen Rebecca have these big epiphanies before that she might not be making the best choices, such as "I'm the Villain in My Own Story." How will this time be different for her?

McKenna: I think in all those cases she just grabbed at another thing. So it's like, "Oh, I'm going to be a villain. OK, that's something I can understand. I can tell you 20 movies where I saw a villain." And the same thing with the Fatal Attraction narrative. That's a narrative. So even if it's a tragic narrative, it makes some sense to her. It's something that she can put in some kind of category. But this one, it ends up having no meaning other than the nothingness and the emptiness and the sadness and the loneliness that she feels after.

And it's funny, we were talking about this song with the director [Joseph Kahn] and we were spit-balling ideas with me and the director and Adam [Schlesinger] and Jack [Dolgen] and Rachel, the songwriters, and we started talking about what the song would be, and I started to weep because I feel like the Groban song is the show's way of saying "someone's still here and someone still cares about you." You think it's all gone and all over, but the story is carrying you forward and the story does have its arms around Rebecca still. She may not know it in that moment, but her story does go on. That was a very emotional moment for me, and for Rachel too, because we love her. She makes terrible mistakes, but we love her, and I think the audience understands her and understands why she makes these terrible mistakes, because we all do. She tries so hard to learn from her mistakes, she tries really hard, but she does have a tendency to slide backwards. And we all get in our own way, so I think it's the most relatable thing, even though it's the most extreme version.

Swimfan is one of my favorite stalker-thrillers. Why did you decide that movie, specifically, was the perfect jumping off point for Rebecca's plan in this episode?

McKenna: The touchstone for people in my generation is definitely Fatal Attraction, but for the younger people, Rachel and the younger people in the room, it was definitely Swimfan, and everyone seemed to know it very well. And then at some point "Swimchan" came to be and it seemed even more perfect somehow... And the song in the credits sequence song, the "Swimchan" song, was a song that we briefly considered for the credit sequence, but it's so focused on the revenge aspect that we felt it didn't cover the whole season. But it was such a good song, the melody and the vibe of it, and then a bunch of those lyrics are just Rachel went into the studio and kind of improvised her feelings... She sort of improvised what Rebecca might think her feelings were, but she just can't quite articulate "scary, sexy lady." She doesn't quite have the words to wrap herself around it. And then Adam built this track for it that is this perfect moody, revenge-y sounding song. So at that point, she still has a story to tell herself and the story is that she's in the more dangerous part of the thriller.

Rebecca tells Josh that she only recreated all the thriller movie tropes to get his attention so that they could finally talk, which is so much more upsetting to me than if she was just doing it to get revenge.

McKenna: That romantic rejection, you no longer have that connection to the person and it's not a democracy. There's two votes. You vote yes, they vote no. There's no tie-breaker. And she did not get the choice to sever her connection to him. He did. And that's extremely frustrating. And of course, we don't all behave like Rebecca does here, but everyone knows the intense pain of losing your connection to someone. And one thing that we have talked a tremendous amount about, Rachel and I and the writers in the room, when you're behaving this way towards somebody in a very vengeful manner, what's your endgame? On what planet do you think they'll suddenly turn to you and go, "You know what? Great points!" You're scorching the connection you had to that person in hopes of preserving your connection to them, and that makes no sense, but it's never stopped anyone from doing it.

Josh confronts Rebecca about stalking and harassing him, but he still won't actually talk to her about why he left her at the altar. Do you think it's possible for Rebecca to move on without getting that explanation from Josh?

McKenna: A lot of the things she does in this episode are pretty terrible, bordering on criminal at times. But it happens to intersect really badly with Josh being a coward, and he is, until this point, unable to take responsibility for what he's done. At the point her behavior really becomes stalking, I'd say the onus is no longer on him. But in their previous interactions, he's really never explained why and how he left her. So I would say at the point where her behavior becomes really extreme, he owes her nothing anymore and he's definitely her victim in this episode. But leading into that, there's a passivity to the way he left her that really enflames her and she's somebody who is so terrified of being abandoned and really doesn't know how to process having been left by him.

Rebecca does decide to go home to her mom at the end, but Rebecca's mom can be very blunt with her and not always the most supportive or understanding. Do you think that tough love is what Rebecca needs right now?

McKenna: It's a heartbreaking episode, and one of the things that's heartbreaking about it is that the audience knows that she's headed somewhere that is maybe not the most nurturing place and a place that she fled. But she's out of options in terms of having flamed out all her new relationships. Knowing what we know about Naomi, I think we would all be a little nervous about her going. On the other hand, as Paula says in calling her, Naomi is her mother, and I think that Paula is trying to restore some sort of order and understands that she's out of her depths and that Rebecca needs help from someone who is supposed to be there to help her. And [Rebecca and Naomi have] been there before, because Rebecca has had numerous difficulties before that the series has referenced. So to a certain extent, she's going back to a situation that she's been in, in dealing with a mother she's been dealing with her whole life and I think hoping that things will be different this time.

Greg's dad tells Rebecca that Greg is sober, in love and the happiest he's ever been. Why did you decide to give Greg his happy ending?

McKenna: When he left last season, having him be in recovery, he's sort of the first person in the show to take the step forward out of the quandaries he was in. I think she would have always been wondering "did he stick to those things? Did that work out for him?" So I think what's interesting is that even though she really cared about him, I think in a funny way, you're always slightly kind of wanting to hear that your exes are not great. And at some point she says, "everyone gets to be happy but me," and I think that's part of Rebecca's mindset and feeling — that everyone has a center of contentedness that she doesn't have, whether that's real or not. That's how she tends to frame it.

There are fans out there who still hope for a Greg and Rebecca romantic reunion. Do you think sleeping with Greg's dad killed any remote chance of them getting back together?

McKenna: It's not great. It's probably not the first thing you would do. It remains to be seen. Lots has happened between them. In a funny way, she was reaching out to a connection to him... by being with his dad. In her own funny way, "I just called to say I love you by sleeping with your dad." I think that in some way she's scorching the earth. We were always talking about it like she's sliding off a mountain and she's grabbing at roots stuck in the side of the mountain, and she grabs them and they fall away and Marco is the last thing she grabs before she falls.

Speaking of scorching the earth, Rebecca really lashed out and said cruel things to all of her friends, but what she said to Paula was particularly hard to hear.

McKenna: Horrible, just horrible. The actors really suffer when they have to do that, also. It's really hard for them because they love each other. But look, I'm biased. I think she's so brilliant. But the acting that Rachel does in that scene where she's being so unspeakably awful, but you see the pain that's behind her eyes, you see that this is a cornered animal, that she does love these people but she needs to lash out at them to stave off her feelings about herself, I really think that scene is a tour de force for Rachel.

How much truth do you think was in Rebecca's insults, and how will Paula grapple with what Rebecca said?

McKenna: It's interesting. We've always talked about [Rebecca] as a pebble in a pond and it's kind of for better or for worse. In many ways, the things that Rebecca has said or done has helped people and helped them move on and find things in their lives, particularly Darryl I would say. But in many ways, she's been a bit of a dervish who hasn't really had to take responsibility for the things she's done. And so this is a thing where some of the things she says really do hit home and some of the characters will take them in more than others and it will affect how they think about themselves, but I think the characters also know that she's lashing out.

Even after reading the folder, Nathaniel (Scott Michael Foster) stays at Rebecca's house in case she returns. What does that say about his feelings towards her?

McKenna: I think it says that he really cares about her, but I think it also says that he doesn't really understand those sorts of things. He doesn't really understand the mental illness very well. He was raised in a pretty repressed environment and he kind of admires her high emotionality because it's something he doesn't have access to, so I don't think he quite grasps what's in that envelope.

Is it possible for them to pursue a relationship at the moment, or will Rebecca be prioritizing her own health before romance for once?

McKenna: Well, it's not a great moment for romance. I don't know if this is the right time to kick off a romance, but that's never stopped her before. Yeah, figuring out her priorities — she really thinks she's burnt every bridge, and in the next episode we get to see how the characters deal with Rebecca not being there and being at home. Rachel and I, in taking on some of the romantic comedy tropes, a feeling that we always share is that her obsession with love is a manifestation of her other mental health issues as opposed to a sincere quest for love by a stable person. And her drug of choice is certainly love and romance and boys, and that's something that she has used to mask her true feelings numerous times. And at the end of this episode, she says to Josh, "I don't know what my life means without you. I don't know what to do or how to feel," because this has been her focus since the day she saw him on the street. It's a tough road for her to figure out what's past that for her.

We know that Rebecca is getting diagnosed this season. As lost as she currently is, what does that diagnosis mean to her and how does that affect her quest for an identity and narrative? McKenna: Well, that's coming up. We're going to explore as the things that she was clinging to start to come apart, what are the things that she starts to figure out about herself?

Crazy Ex-Girlfriend airs Fridays at 8/7c on the CW.

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