Jason Tartick has officially moved on from former fiancée Kaitlyn Bristowe, and she’s not taking it very well.

Shortly after Jason, 35, went Instagram official with new girlfriend Kat Stickler on Wednesday, June 12, Kaitlyn, 38, told friends in a private Facebook group, “It’s actually hurting more than you know and for reasons other than most know,” as seen in screenshots from her verified account viewed by Page Six.

The former Bachelorette added in another comment that she had “some held on anger and resentment” that she is “working through.”

Jason hard launched his romance with Kat, 29, in two loved-up Instagram photos. He was seen wearing a white tank top while cuddling his new girlfriend in his arms as they stood in front of a bathroom mirror. In a second snapshot, the former banker planted a kiss on bathrobe-clad Kat’s cheek. “Heart is full,” Jason wrote in the caption.

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Bachelor Nation members and fans cheered on the couple’s hard launch. Former host Chris Harrison commented, “Here … we … go!” about Jasons first relationship since his August 2023 split from Kaitlyn, while Bachelor finalist Vanessa Grimaldi wrote, “Awwwwww” with a red heart emoji.

“I’m so thrilled for you both!!!” one fan gushed, while another added, “This might break the internet!!! Love this so much, two wonderful people that radiate happiness and love.”

Kaitlyn Bristowe 'Hurting' Over Jason Tartick and New Girlfriend
Courtesy of Jason Tartick/Instagram

Jason and Kat were first linked when she attended his New York City wrap party for his new book, Talk Money to Me, on April 19. When giving shout-outs to those who were present, including several Bachelor Nation members, the author added, “We got the TikTok celebrities [here], like Kat Stickler,” to a round of cheers.

Kaitlyn and Jason announced on August 6, 2023, that they ended their engagement and were splitting after nearly four years together.

“Continuing our friendship is incredibly important to both of us. We feel grateful to be ending our engagement with love and respect for each other,” the pair wrote in a joint Instagram post. “It’s heartbreaking and sad to say goodbye, but our care and admiration for one another will never die.”

Kaitlyn later called out Jason for not “protecting” her after he shared a heartbreaking video moving out of her Nashville home on August 23, 2023. “I’ll tell you what physically and mentally sucks,” he said, as the video showed the former couple’s two dogs, Pinot and Ramen, looking confused and forlorn.

“I share this bc although I said I was OK, I wasn’t,” the Buffalo, New York, native added in the caption, thanking a close friend who helped him move his belongings into a storage facility.

“We talked about protecting each other through it because, of course, when you go through breakups you want to have your side and someone to have their side,” Kaitlyn said during the September 19, 2023, episode of her “Off the Vine” podcast. “To justify it and say all these things. We really agreed on protecting each other.”

“When he was, kind of, leaning into that sad — I was like, ‘Bro,’” she said. “It didn’t protect me because it made me look like I was taking the dogs away from him.” The duo shared in their breakup announcement that they would continue to look after their golden retrievers together.

The pair came face to face for the first time since their split at Chris’ wedding to Lauren Zima three months later.

“It was friendly, it was cordial, it was respectful,” Jason said of his encounter with Kaitlyn during the November 13, 2023, episode of his “Trading Secrets” podcast.