During an appearance on PEOPLE (the TV Show!) on Friday, Metz, 41, opened up to Segun Oduolowu about her character Kate Pearson's storyline and what is to come for her marriage with Toby Damon (Chris Sullivan).
"It's going to be quite a ride," Metz says. "I mean, obviously, you saw that Kate has now remarried to another man in that season finale of last year. When you get to sort of see how things dissolve and how it unravels, you need to brace yourself because while neither Kate nor Toby are right or wrong, you know, people just sort of grow apart if they don't grow together."
The actress and singer adds, "It's gonna be a doozy and it's gonna be really difficult to watch cause it's been difficult to perform. So just brace yourself, folks."
Metz also spoke about the process of co-writing an upcoming Kate-focused episode and how she drew inspiration from her previous marriage to screenwriter Martyn Eaden.
"I've always wanted to co-write an episode [and] write for TV or film," she says. "And so for it to be a Kate-centric episode, I really pulled from a previous marriage. My first marriage — not that I'm married now, let me be very clear — [was] to a wonderful human who was an angel, but also we just grew apart. And so there's a lot of parallels in Kate and Toby as my former relationship goes too."
Paul Archuleta/Getty Images Chrissy Metz
To make the upcoming episode even more special for the actress, Metz's costar and on-screen mom, Mandy Moore, will be directing.
"[Mandy is] 'my mom' and my friend and somebody who I've revered for a long time and respect," Metz says.
"[She] just has been so fun and she's so kind and gentle, but also speaks the shorthand of an actor who just wants the best performance," notes Metz, who recently partnered with Capital One Auto Navigator to share her story and help people find easy ways to purchase a car.
Matt Winkelmeyer/Getty Mandy Moore and Chrissy Metz
News that Metz would be co-writing an episode in the sixth and final season of This Is Us was first announced last November.
"It's really exciting to support fellow actors and people that you love trying new things," Metz told PEOPLE at the time. "For me in particular, obviously, writing has been a very new venture, but I'm very excited."
"Dan [Fogelman] is such a great mentor, and I get to write with Casey Gettinger and David Windsor, who are our writing team. It's been really wonderful," she conitnued.
For five seasons, audiences have seen Metz portray Kate through her ups and downs in her marriage to Toby and complicated family dynamics as a Pearson sibling and daughter.
Ron Batzdorff/NBC Kate and Toby on This Is Us
Fans got a glimpse of her marriage's fate in the season 5 finale when they discovered in a five-year flash-forward that Kate gets remarried to Phillip (Chris Geere), her boss at the music school for the blind.
"While you can fall in love with a couple, there's so much going in a relationship and even things they hadn't noticed. But as we grow, you either grow together or you grow apart. That's the sad truth and it's bittersweet," Metz previously told PEOPLE of Kate and Toby. "I think they're both interested in each other's happiness and have been chasing their own happiness for a long time so that's what's most important."
The star added, "I think it's important that we can find love in different ages, stages, times and places. And maybe in the unexpected."
This Is Us airs Tuesdays at 9 p.m. ET on NBC.