How does 'Firefly Lane' end? Stars break down the tearjerker of a series finale

"Firefly Lane" has taken Netflix viewers on an emotional rollercoaster since it first premiered in 2021, and the final season is the most heart-wrenching of them all.

Season Two Part Two, which premiered on April 27, follows the end of Kate (Sarah Chalke) and Tully's (Katherine Heigl) journey together.

Ready to find out how their story ends? Grab your tissues, friends, because we're breaking down all the highs and lows of the series finale, featuring commentary from the stars themselves.

1970s: Tully and Kate get into college

Kate and Tully celebrate when they both get accepted to the same college. Tully also learns that her mother Cloud (Beau Garrett) was released from prison. However, she didn't come to visit her and Tully feels hurt. Kate cheers her up and they go on a celebratory bike ride.

The Mularkeys bid the girls farewell as they prepare to drive off to college. Unbeknownst to the teenagers, Cloud is parked nearby, watching them proudly. "Go get 'em, girls," she says as they leave.

According to Chalke, Roan Curtis (young Kate) and Ali Skovbye (young Tully) are just as tight behind the scenes as they appear to be on film.

"They are such close friends in real life now," she tells TODAY.com.

Reflecting on the young actors' bond and her own friendship with Chalke, Heigl thinks having the original "Firefly Lane" book by Kristin Hannah as source material helped all the stars to form close relationships.

"You sort of dive into the minds and hearts and ambitions of these characters in that way first. And I feel like we all into it already a little bit in love with each other. We just really got lucky that it could blossom," she says.

1997: Tully gets her own talk show and moves back to Seattle

Tully scores her own talk show and is set to film it in New York City. On the last day at her old job, she gets stuck inside an elevator and it plunges nearly 20 stories, leaving her to reevaluate her life. She decides that she's sick of New York and misses Kate, Johnny and Marah, so she convinces the studio to film her show in Seattle.

Tully asks Johnny to be her producer and Kate is offended that she didn't ask her. When Tully asks, though, she jokingly declines. The pals celebrate their reunion with a dance party to one of their favorite songs: ABBA's "Dancing Queen."

Kate’s mother encourages her to go back to work and says she has “so much potential.” She then goes to visit Tully on the set of her show and realizes that she can make a difference after picking up on how uncomfortable Tully seems with her new crew. Kate gets to work and provides her best friend with some harsh but necessary feedback to help her shine.

2006: Kate's cancer progresses and she gets some heartbreaking news

After suffering from a seizure, Kate learns that her cancer has progressed even more and she has weeks (months, if she’s lucky) left to live. Tully is more determined than ever to have Kate begin the experimental trial that Danny (Ignacio Serricchio) just got her into. Johnny regretfully tells her that the doctors she’s now disqualified for the trial since her cancer has spread too far.

Tully doesn’t take the news well and lashes out at Johnny to cope with her pain. “F--- you for giving up on her. You were never good enough for her, Johnny,” she says. After talking to Kate, though, she soon realizes that there’s nothing else she can do for her best friend but stand by her side since Kate has accepted her fate.

"She says that to Tully, who does not feel that way and wants to keep fighting," Chalke says. "That was probably the most emotional scene we shot."

The moment was equally impactful for Heigl.

"I just felt so much sorrow for Tully, who just did not want to accept it. I could barely get through that scene," she recalls.

Back at home, the family attempts to make Kate as comfortable as she can be in her last weeks and they spend as much time together as they can.

Kate decides to write a book about her life so her daughter will always have something to remember her by. It's a beautiful addition to the story, but one that was certainly hard for Chalke, who has two children, to embody.

"It’s every mother’s worst fear — not being able to raise your kids and see it through. That storyline specifically, I love how it was handled and how it just felt very true to the story of Marah and her mom," she says.

2006: Tully and Danny profess their love for each other

Things are going pretty well for Tully and Danny, but when Kate learns that she only has a few weeks left to live, Tully gives her best friend her full attention and neglects her budding relationship with Danny. He tries to call her repeatedly. Kate encourages her to answer, but by the time she does have a proper conversation with Danny, he tells her that he’s preparing to move to New York for a job opportunity.

Tully gets vulnerable and pleads with Danny to stay. He obliges.

2006: Kate loses her battle with cancer

One day, Kate asks Tully how she’s coping with knowing that she will lose her soon. Tully breaks down and says, “I don’t know who I am without you. I don’t know how to exist without you. I’m never gonna be ready.”

Kate says that she thinks she's "getting off easier" since she doesn't have to "face a world without (Tully)."

While looking back on the moment, Heigl explains how she connected to this line.

"Kate is missing out on so much of the rest of her life, but in a way for those of us left behind, it feels like they got out easier than we do," she says.

As the two friends sit outside one day, Tully gets up to go inside the house for a moment and when she comes back, Kate has passed away.

Beforehand, Kate gave Johnny some very specific instructions for her funeral. When Tully shows up to the church, she tells Johnny she doesn't think she can go inside to the service. He says Kate predicted that would happen and hands her a box.

Tully sits down on a bench outside the church and examines the contents of the box. First, she pulls out a letter from Kate and marvels at the book she wrote about their friendship. Next, she lights up a cigarette and kisses a photo of '70s heartthrob David Cassidy, per Kate's instructions.

Finally, she turns on an iPod and listens to a playlist Kate curated, which kicks off with one of their favorite songs, ABBA's "Dancing Queen." Per Kate's instructions, Tully busts a move as she holds back tears.

Recording the voiceover for this scene was an emotional experience for Chalke, who tells TODAY.com that she had a hard time holding back tears when she got to one line in particular.

“I’m reading it and every time I got to the line of ‘Take care of Marah for me,” I couldn’t make it work. I’d be like, ‘OK, let me start again. I got this.’ And then I would start again and be like, 'OK, let me just dance for four minutes.' That piece was so emotional," she says.

Heigl describes the experience of filming the scene as "brutal."

"The hardest part of this part of the season, for me, it was just trying to rein it in and not be a sobbing, weeping mess," she says. "I think a lot of that just came from how much I love Tully and Kate, how real it all kind of felt to me by that point, how much I love Sarah, how much Sarah informed Kate. and how it all just felt maybe a titch too real."

Although it might've been difficult to film, the ending hit the right mark for the stars.

"This book was really, really important to me and I really, really deeply love and respect the novel. So I loved that that scene was as written in the book down to the letter Kate leaves Tully, like word for word. I think it’s a beautiful ending," Heigl says.

Chalke echoes her co-star's sentiments and says she loved "everything about it."

"I loved that you don’t go inside at all to the funeral; you stay outside with Tully. When I was watching it, it felt so hopeful," she says.

Chalke also had strong praise for the "balance" that Heigl brought to the tearjerker moment.

"I thought it was so beautiful. I thought (Heigl) did such an amazing job," she says.

2016: Marah gets married

On Marah's wedding day, we see Kate and Tully talking to each other as they look into a mirror. The scene takes place before we realize that Kate has died and it's implied that she is still alive.

“I can’t believe it’s been 10 years. Ten years since our horrible fight. Ten years since I got sick. And now my little girl is all grown up,” she says as the two friends look in a mirror.

Ever the proud godmother, Tully says, “We did it Mularkey, we raised a great girl.” She then reflects on everything Marah has been through over the past decade, including college and law school.

Kate thanks her best friend for “sticking with her” through everything.

“It wasn’t me. Everything good that she is, that’s because of you, Kate,” Tully replies.

We soon realize that Tully imagined the whole conversation as she turns when there’s a knock on the door and she looks back to see herself — and no Kate — in the mirror. Later, we learn that Kate died 10 years before her daughter's wedding.

This was one of many emotional scenes throughout the season, and Chalke says the cast filmed many scenes multiple times for a very important reason.

"Some we'd do them much less emotional and then we'd have them a little bit more emotional, maybe welling up, then (some were) just full on crying so that there would be some options in the editing room," she says.

To cope with all the heavy emotions, Chalke made sure to carve out a bit of time each day to focus on her mental health.

"When I had any free time my favorite thing to do was just go hiking with my dogs and breath in the fresh air. The other thing for me is taking a hot bath every night. Then at the top of the list, it was snugging my babies," she says.

This article was originally published on TODAY.com