Viall says Kristina "hit on" his brother, but she claims he made the first move.
In a series of Instagram Stories posted Wednesday night, Kristina called the fellow reality star an "asshole," after he accused her of being a "diehard" fan who hit up his brother Sam before appearing on Nick's season.
The drama began after Viall tuned into the latest episode of "Bachelor In Paradise," where Kristina said costar Luke Stone was "nicer, cuter and easier to talk to" than Nick.
Nick kicked off his podcast, The Viall Files, on Wednesday by reacting directly to Kristina and criticizing the show for highlighting that conversation. "What the f--k?" he began, "I have some thoughts."
"I honestly am probably more annoyed with the show airing it," he said, before taking aim at Schulman. "I'm not surprised Kristina had that to say. In fairness to Kristina, I probably wasn't easy to talk to on my season with Kristina since she decided to tell me that she slid into my brother Sam's DM before our season of 'The Bachelor.'"
"I don't know what her intentions, but she was just like, 'Yeah, I slid into your brother's DM and I was talking to him a little bit,'" he claimed. "And I was like, 'That's super weird."
He went on to say that he "sensed" Kristina was "a diehard 'Bachelor' fan" before coming onto the show, calling it "honestly kind of awkward." Viall added, "If you tell me you hit on my brother on a date, I might not won't be the most conversational."
He also called it "a bit frustrating" to see Schulman and other past "Bachelor" contestants "throw their leads under the bus."
Kristina hit back with a few claims of her own after catching wind of the podcast, taking to her Stories to share her side of the situation with a video captioned, "Let's clear this up once and for all."
"One, Nick Viall, you don't know me, the person being portrayed on TV, you can't say with certainty that's who I am because you don't know me," she began. "Second, I was the one to tell you that your brother messaged me, not the other way around. And third, you were the asshole when I was talking to your guy, your 'wingman' and you sent him a message saying, 'Dude, f–k her,' in reference to me. So disrespectful."
"Where do you come from when telling I'm the terrible person," she then asked, insinuating he's actually the one in the wrong here.
Viall has yet to respond to Kristina's claims.