Rep. Keith Ellison -- deputy chairman of the Democratic National Committee and a candidate for Minnesota attorney general -- has denied allegations that he abused his ex-girlfriend, Karen Monahan. On Thursday, Monahan, 44, spoke on camera for the first time about an incident she said happened nearly two years ago.

Monahan said she has video of what happened but that it's too traumatic for her, so she has chosen not to share it with anyone. CBS News has not seen the video.

Monahan said that in September of 2016, she and her then boyfriend, Ellison, got into a heated argument that scared her. She said it started when he came into a room where she was laying on a bed, listening to a podcast. He asked her to take out the trash and when he asked if she heard him, she shook her head.

"He looked at me, goes 'Hey you f***ing hear me … and then he looked at me, he goes 'Bitch, get the f*** out of my house,' and he started to try to drag me off the bed," Monahan said. "That's when I put my camera on to video him."

Karen Monahan CBS News

She said she called a friend after the incident and told them she was "at the lowest of the low."

Monahan said she saved the video on her computer. This past Saturday, Monahan's son, Austin, posted a message on Facebook saying that in the middle of 2017, he found the video, almost two minutes long, showing Ellison dragging his mother off a bed and telling her to get out of his house.

Monahan said she should not have to release the video of the incident in order to be believed. She believes her words should be enough.

Monahan told CBS News she has the video on a thumb drive.

Ellison spoke to CBS Minnesota about the allegations.

"I'm mortified, absolutely stunned that she would say this," he said.

When asked if he ever dragged Monahan, Ellison said "no, absolutely not."

He also said there "couldn't be such a thing" as a video "because I never did that."

CBS News asked Monahan why she decided to speak now.

"I followed my gut," she said. "The gut that I kept trying to push down."

Monahan said she never reported the incident to police and said being dragged off the bed was the only time Ellison got physical with her during their three-year relationship.

"He didn't apologize for putting his hands on me ... one is enough," Monahan said.