The woman, Porter's first wife Colbie Holderness, spoke out after Tuesday's report in the Daily Mail that quoted his second wife Jennifer Willoughby, about how he had on one occasion dragged her wet and naked out of a shower during an argument.
The Daily Mail ran photos of Holderness with a black eye that she resulted from Porter hitting her.
Holderness revealed to DailyMail.com that she was interviewed by the Federal Bureau of Investigation - as was Willoughby - about her marriage after Porter was tapped for his current White House position as White House staff secretary and required security clearance - clearance which he has not received.
In recent weeks he was closely involved in preparations for Trump's address to business leaders in Davos, Switzerland.
The website reported that Mr Porter is now dating Mr Trump's Communication's Director, Hope Hicks. The White House staff secretary - who has access to and reviews presidential correspondence - never received full security clearance, and the allegations were the main reason why, two sources tell CBS News chief White House correspondent Major Garrett.
"These outrageous allegations are simply false", Porter said in a statement.
"I took the photos given to the media almost 15 years ago and the reality behind them is nowhere close to what is being described", Porter said Wednesday.
"I've been transparent and truthful about these vile claims, but I will not further engage publicly with a coordinated smear campaign". She said Porter's departure would not be immediate but would come at a date to be determined. He lashed out and was really angry, and both under his breath and explicitly to me called me a "f-- b--" and "f-- ridiculous'.' He accused me of not caring about him or not caring about his needs".
Statements from White House Press Secretary Sarah Sanders also semed to evolve as the story grew in intensity and Porter was forced out.
It remains unclear when he will officially depart the White House.
Holderness alleged Porter wasn't physically abusive until their honeymoon.
But Willoughby said she "definitely" wanted to see Porter stay in the White House.
The White House staff secretary also helped the president follow protocol. "As has always been our policy, we do not comment on security clearances", she said. Rob Porter has been effective in his role as Staff Secretary.
"I am heartbroken by today's allegations", Senator Hatch said in a statement.
In a statement, Porter denied the allegations, which were first published on Wednesday by the Daily Mail. Mike Lee, Rob Portman, and Hatch.
'In every interaction I've had with Rob, he has been courteous, professional, and respectful. I don't know the details of Rob's personal life. A simple "I'm troubled, but he's innocent until proven guilty" would have sufficed but instead Kelly opted for "Rob Porter is a man of true integrity and honor, and I can't say enough good things about him". And on Tuesday, the Utah Senator denounced the Daily Mail's report of domestic violence allegations against Porter - comments which he walked back Wednesday after more information was reported.
Before joining the White House, Porter worked for Sen.