The mother of U.S. Army Sgt. La David Johnson—a soldier who was killed in an ambush in Niger earlier this month—has confirmed reports that President Donald Trump said her son "knew what he signed up for" when talking to Johnson's widow, a comment which sparked outrage after it was first relayed to the media by Rep. Frederica Wilson (D-Fla.).

"President Trump did disrespect my son and my daughter and also me and my husband."

—Cowanda Jones-Johnson, Sgt. Johnson's mother

Wilson said she heard Trump's comment as she rode with Sgt. Johnson's widow Myeshia to the Miami International Airport, where Johnson's casket arrived late Tuesday. The reported comment immediately sparked a firestorm of condemnation on social media, with critics calling the remark "repulsive" and "detestable."

Wilson told the Washington Post that she wanted to "curse [Trump] out" when she heard his comment, which she said made Myeshia Johnson cry.

When the Post asked Sgt. Johnson's mother, Cowanda Jones-Johnson, who was also in the car during the phone conversation, if Wilson's account was accurate, she simply replied: "Yes."

"President Trump did disrespect my son and my daughter and also me and my husband," she added.

The White House initially refused to confirm or deny the story, but Trump took to Twitter early Wednesday to claim that the Florida congresswoman "totally fabricated" the story, adding that he has "proof."

Wilson fired back shortly after Trump's tweet in an appearance on CNN, saying that she also has proof. Wilson went on to say that Myeshia Johnson turned to her after the phone conversation with Trump ended and said "he didn't even know his name."

"Now that's the worst part," Wilson said. "This man is a sick man. He's cold-hearted, and he feels no pity or sympathy for anyone."

Watch Wilson's CNN interview: