"Not only were we engaged but it's like, man, I lost my best friend too," Shawn, 31, said in a sneak-peek clip obtained by Us Weekly of his recent appearance on an episode of Ben Higgins and Ashley Iaconetti's "Almost Famous: In Depth" podcast, which will be released January 27.
It's been nearly three months since Kaitlyn and Shawn announced they had decided to call off their engagement in November 2018.
"I didn't actually think it was going to be this difficult [to talk about]," Shawn said of his breakup with Kaitlyn.
"I knew it would be hard, but I guess once you actually start opening up about it a little more, it makes it that much harder."
The fitness trainer and Kaitlyn got engaged during the The Bachelorette's eleventh-season finale that aired on ABC in 2015.
Rumors began swirling the couple had split in Summer 2018, shortly before Kaitlyn and Shawn made their official public announcement.
"We were working through things during the summer, but... we were still together," Shawn clarified of the fuzzy timeline. "We ended up, I would say, officially breaking up [in] September and then announcing it in November."
"You know, we were this team and we got through a lot of stuff together, but then just, like, in an instant it's all gone."
Shawn admitted it's been really hard to avoid what Kaitlyn has been up to in her love life, although he tries his best to ignore "the outside noise."
"It's nerve-racking every time I pick up my phone. I haven't been on Twitter in months just because I don't want to scroll the mentions," Shawn said in the podcast clip.
"Then I go on Instagram -- you know, I do that for business purposes -- [and] obviously get caught with scrolling, and that's always tough because you have a pit in your stomach... I do not go to the Discover page. I learned that pretty quick. Haven't been there in a while."
Shawn, however, noted he hopes Kaitlyn will be happy and that he will eventually find his perfect match.