Scott Disick/Instagram Scott Disick and son Reign
On Thursday, the 38-year-old Keeping Up with the Kardashians alum shared a since-expired post on his Instagram Story, where he said that he was spending quality time with son Reign Aston, 6, after school, as seen in a screen grab of the post obtained by E! News.
"After school break down with reign," Disick wrote alongside the shot, which showed the father-son duo hanging out together on separate chairs.
The post from Disick marked his first since news broke that Kardashian found her happily ever after with Barker, 45, when the Blink-182 drummer proposed at a beachside hotel on Sunday evening.
In addition to Reign, Kardashian, 42, and Disick — who dated on and off for nearly a decade before breaking up for good in 2015 — share two other children together: son Mason Dash, 11, and daughter Penelope Scotland, 9.
Presley Ann/Getty; Jeff Kravitz/MTV VMAs 2021/Getty
Barker proposed to Kardashian over the weekend at the Rosewood Miramar Beach Hotel in Montecito, Calif. The mother of three announced the news on Instagram, sharing photos from the romantic moment with the caption: "Forever @travisbarker."
Following the proposal, a source told PEOPLE that Disick is distancing himself from his ex's famous family in order to "make his peace" with the engagement news.
"Scott hasn't really wanted to deal with Travis and Kourtney because he didn't feel like he'd have to," the source said. "At first, it seemed like it was just a casual relationship to him, nothing serious. So he pretty much put that on mute. Hasn't been giving it too much brainpower, thinking that eventually, they'd break up."
"But that didn't happen and now he's being forced to deal with it, which is uncomfortable," the source continued. "He knows he has to lean into the discomfort and get past it. He understands that it's not Kourtney's job or Travis's job to make him okay with this. It's his job, and if he's going to co-parent with Kourtney, which he has been, he has to process this and make his peace with it."
The insider added that "distancing himself from the family" is a way for Disick to achieve that. "It's not about them, it's not about Kourtney. It's about him needing some time to process this and deal with it on his own, without them," the source said. "He'll come around soon."
RELATED VIDEO: KUWTK Reunion: Kourtney and Scott Address Each Other's New Relationships for the First Time
Another source also told PEOPLE earlier this week that Disick is "not happy about the engagement."
"Scott never approved of Kourtney dating Travis. He has struggled with their relationship," the source said. "He always had this idea that he and Kourtney would eventually get back together. He was pretty shocked when he found out that she was dating Travis."
During the two-part Keeping Up with the Kardashians reunion in June, Disick gave the Poosh founder his blessing to move on with other people: "I think if you really love somebody, you want them to be happy no matter what. So I do give her a blessing to be happy," he told host Andy Cohen at the time.
"Yo is this chick ok!???? Broooo like what is this," Disick allegedly wrote to Bendjima, 28, sharing a photo of Kardashian and Barker kissing, to which Bendjima allegedly responded, "Doesn't matter to me as long as she's happy. P.S. I ain't your bro."