"This morning was not an easy one," he told fans on Instagram.

By Claudia Harmata
April 25, 2019 08:25 AM

John Galecki has a good reason to cry.

After 12 seasons, The Big Bang Theory is airing its final episode on May 16. And from the looks of some of the cast’s social media, it’s going to be an emotional one.

Galecki uploaded a tearful photo to his Instagram late Wednesday night, after the show’s final table reading.

“This morning was not an easy one,” Galecki, 43, who plays Leonard on the show, wrote alongside the photo. “The final table reading for The Big Bang Theory. So very sad. So very grateful.”

He wasn’t the only cast member moved to tears during the final table reading. Kaley Cuoco, 33, who plays Penny, also shared a series of emotional photos on her Instagram. In one, she is visibly crying while holding the script to the finale episode, captioning the image, “Post table read for The Big Band Theory finale episode.”

Actress Courteney Cox responded to Cuoco’s post, reminiscing on the Friends finale.

Kaley Cuoco Instagram Big Bang Theory
Credit: Kaley Cuoco/Instagram

“Awww I remember that feeling…and you guys have been together even longer,” she wrote.

Last month, the CBS sitcom surpassed Cheers as the longest-running American multi-camera sitcom when it aired its 276th episode.

Showrunner Steve Holland told Entertainment Tonight that the last few episodes will be an “emotional journey” for the cast and viewers alike, as they tie up the storylines for each character.

RELATED VIDEO: ‘The Big Bang Theory’ Ended Because Jim Parsons Wanted to Leave: Report

“We’re excited and nervous and, like everybody who’s watching, we love these characters so much and we want to give them a send-off that they deserve,” he told the outlet in February.

And Cuoco and Galecki confirmed in their posts, these episodes are going to be tear-jerkers.

“Prepare yourselves … for a finale that has truly given me a loss for words,” Cuoco captioned a photo of the finale script covered in tissues.

According to Entertainment Weekly, CBS was negotiating two more seasons, but star Jim Parsons — otherwise known as Dr. Sheldon Cooper — was ready to say goodbye to the sitcom.

CBS had no comment, and a rep for Parsons did not respond to PEOPLE’s requests for comment at the time, but the actor addressed the show ending with a lengthy note on Instagram, saying he will miss “all of this more than I can say and more than I can know at this time.”