Actress tells James Corden Chuck Lorre is currently writing the series finale.

Mom is the mother of all maternal sitcoms, and its abrupt cancellation rocked star Allison Janney, who revealed Wednesday night the real reason she suspects the show is ending after 8 seasons.

"I'm sad. I wish we'd had at least another year for the writers to have that much time to ramp up to the ending," Janney told James Corden on CBS' Late Late Show Wednesday.

"We sort of found out sooner than we thought we would hear," she continued. "We thought, surely, they're going to want more Mom, and they decided not. There are so many reasons behind that—most of them probably money. But, I know that [series creator] Chuck Lorre is writing the final episode and we're right now filming the third to last episode."

Janney premiered on the show back in 2013 alongside co-lead Anna Faris, with the pair playing a mother-daughter duo rebuilding their lives together as they both recover from substance addiction.

Faris surprisingly departed the show prior to its season 8 premiere last year, but Janney still has fond memories from the set as production winds down.

"I'm having a lot of moments where I'm just standing on set and taking it in and looking at all the faces I've looked at for eight years," she said, adding that she's grateful to real-life addicts whose lives were impacted by the show's story.

"I have a real community of people that I love and it's going to be very hard [when] all of a sudden it's gone," she continued. "No matter how much I prepare myself for it, I know I'm going to be in tears, just buckets of tears."

Though Janney's tenure on Mom is coming to an end, she's maintained a healthy film career during her time on the show, including an Oscar-winning role in I, Tonya and her wild turn as a fam-obsessed widow in her longtime friend Tate Taylor's new comedy Breaking News in Yuba County.

A representative for CBS didn't immediately return EW's request for more information on Mom's cancellation.

Watch Janney's appearance with Corden above.

Hear more on all of today's must-see picks, plus what rapper Saweetie is watching, in EW's What to Watch podcast, hosted by Gerrad Hall.

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