Just one day ago, Jordan Kimball was excitedly planning a wedding to his fiancée, Jenna Cooper. The date was set, the venue was chosen and he was looking into catering options.

Then Kimball was blindsided Tuesday morning when a story on blog Reality Steve emerged alleging Cooper was also in a relationship with another man. The story included graphic text messages that were allegedly between Cooper and the unidentified man.

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The story also alleges that Cooper claimed her relationship with Kimball was fake.

“It felt like a body drop,” Kimball tells PEOPLE of learning about the allegations. “I got taken down. I’m weak in the knees and I feel like I have rocks in my stomach.”

In an exclusive statement to PEOPLE, Cooper denies the claims, stating, “I am aware of the allegations being made against me and they are simply untrue. I am choosing to focus on my relationship right now. Thank you for respecting my privacy at this time.”

Image zoom Jordan proposed ABC

Her fiancé is struggling to believe her. With a shaking voice, Kimball, whose engagement to Cooper aired on Tuesday night’s finale of Bachelor in Paradise, reveals his whirlwind of emotions from the past 24 hours.

“On Monday, I saw something someone posted on Twitter — that somebody was going to be roasted the next night,” says Kimball. “Jenna called me and said she was very anxious about this Twitter post. I talked to her in the middle of the night last night – I said don’t hype yourself up, don’t worry, you have nothing to worry about. I tried to calm her. I went back to bed for a few hours, woke up, had my coffee and she called me again and said she was anxious and felt sick to her stomach.”

Continues Kimball: “She’s in New York. I told her to keep calm. I thought she was just being nervous for no reason. Then I was driving back to Central Florida from Miami and I started getting calls from castmates like Chris Randone. I started getting screenshots sent to me. I didn’t know what to think. I sank in my seat.”

Kimball says he spoke to Cooper, but that he believes the allegations to be true. “I know my Jenna, and I read those texts and in my heart, I know it’s her,” he says. “She was saying she didn’t do it, but hinting towards the fact that there’s a possibility that it happened. In all reality, I don’t expect her to own it.”

For his part, Kimball says he’s overwhelmed by the alleged betrayal, on many different levels.

Image zoom Paul Hebert via Getty

“I would never have expected this,” he says. “I feel sick about it. I just don’t understand why someone would say that they’re better than me and have ill intentions.

“If this whole thing sticks, and it’s true, I will be hurt much more than the depths of romance. I will be hurt as a person and as a friend. There are so many layers to a relationship and right now I feel all of them peeling back.”

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Kimball says he and Cooper were planning an engagement party for next month. “I was going to bring my parents to North Carolina,” he says. “I really feel like I’m going to start dry heaving. I don’t know how to handle this. It really kills me.”

As for any question as to whether the relationship was real for Kimball, the model is definitive.

“There is not even a question about that. This was not a TV romance. This was real. And whether you like me or not, I deserve love. I found it, and this is what happened. So for the sake of anyone who’s ever been in love, be understanding.”

But despite everything, Kimball says he doesn’t yet have an answer as to whether or not they’re still engaged.