Shawn recently opened up to Ben Higgins and Ashley Iaconetti on their "Almost Famous: In Depth" podcast about Kaitlyn and Jason's new relationship, and Us Weeklyobtained a sneak-peek clip of the episode set to be released on Sunday, January 27.
"Seeing everything, it does upset me and it's making me a little angry," Shawn, 31, said in the clip.
Sean admitted it's been hard to wrap his head around the fact Kaitlyn is dating a new guy less than three months after they announced their decision to end their engagement in November 2018.
"[I'm] trying to understand things right now. I guess this goes with her new relationship too. It just kind of makes me question everything that we've had," Sean explained to Ben and Ashley.
"So I think that's one of the major questions that runs through my mind -- just trying to understand that, which I think is tough to understand."
Shawn 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.
Kaitlyn has clearly moved on from her three-year relationship with Shawn, as she revealed on January 16 she considers Jason, a 30-year-old banker who competed on Becca Kufrin's season of The Bachelorette, to be her new boyfriend.
Kaitlyn and Jason began dating earlier this month, and things have been moving fast ever since. Jason recently called Shawn's ex "someone very special," and the pair seem smitten with each other.
"To see her moving on so quick, I just have a tough time understanding why she would be putting this out everywhere or blasting it out all over the place, knowing that it could hurt," Shawn said on the podcast, likely referencing how Kaitlyn often gushes about Jason on her Off the Vine podcast and the pair show PDA on their Instagram Stories.
"It does hurt... but it also helps me to move on knowing that maybe we weren't right for each other and I'll find somebody down the road that will also make me happy."
However, Shawn apparently doesn't harbor any ill will against Kaitlyn.
"I do care about her, so I am happy that she doesn't have to, I guess, deal with, maybe, all the pain and the heartbreak because it seems like she's moved on and she's happy," Shawn pointed out in the sneak-peek clip.
"It does make me a little more comfortable knowing that she's not at home at our empty house, so I look at it from that point of view."
Kaitlyn and Shawn, a fitness trainer, both currently reside in Nashville, TN, while Jason is from Buffalo, NY, but currently resides in Seattle, WA.