The Ulster Unionist Party leader has said he is “ashamed” by historic tweets that have emerged since he apologised for joking about a brothel and a rival’s wife.
Doug Beattie said he had been made aware of “totally unacceptable” tweets he had posted in the past.
The tweets have seen Mr Beattie again accused of misogynistic behaviour.
Earlier, DUP Stormont minister Edwin Poots said his wife was “disgusted” after Mr Beattie tweeted a joke about her that referenced a brothel.
Mr Poots said the tweet by the UUP leader on Saturday night was “incredibly hurtful”.
Mr Beattie apologised on Sunday for tweeting the joke and deleted it.
The Upper Bann MLA reiterated that apology on the floor on the Assembly on Monday, insisting he was “truly sorry”.
However, hours later, he was apologised again after other historic tweets started to circulate.
In a statement, Mr Beattie said: “Since I made my unreserved apology in relation to a tweet at the weekend I have been made aware of a number of historic tweets which I published.
“I am deeply ashamed and embarrassed by the content of these tweets. They are totally unacceptable. They do not reflect the opinions or values I hold today.
“From the time I entered politics I have made a serious effort to increase the representation of women and advocate policies which would improve the lives and wellbeing of all women and girls.
“That is where I stand and I deeply regret the fact that these historic tweets could serve to undermine that position.
“Misogyny is something which must be taken very seriously and dealt with through education, listening and understanding. I am sorry that in the past I have fallen short, but I will continue to listen first and foremost to the voices of women and girls.
“My actions going forward will be consistent with the values I hold.”
The controversial joke on Saturday evening described a fictional scenario involving Mr Beattie and Mr Poots in a barbershop.
It made a reference to Mr Poots’ wife and a brothel.
Mr Beattie claimed the joke was not his own and he was sharing something that had been sent to him.
Mr Poots said he accepted Mr Beattie’s apology, but he questioned his “poor” judgment in posting it in the first place.
“I just don’t know what he was thinking about,” he told BBC Radio Ulster.
“I’m a big boy, I can take a lot of abuse in politics and that’s fine, but we really shouldn’t be drawing other members of people’s families into anything, they have their right to their private life and, unfortunately, that has been infringed when it comes to my family in this instance.”
Mr Poots said his wife Glynis, a nurse, was “disgusted” by the tweet.
“But it’s actually had a bigger impact on the rest of us, her children and myself,” he said.
“Saturday night was the first time our family had been together as a family for four years, because we have two children who are doing voluntary work abroad, and it coincided that they happened to be home.
“We got news of that late on Saturday night and to have someone described as a prostitute, or your mother described as prostitute, it’s not something that people really find acceptable.
“It’s hurtful, my wife was a working-class girl, not a working girl.”
He added: “Having her demeaned like that is something that personally I find incredibly hurtful.”
Mr Beattie gave a statement at the start of Assembly business on Monday.
“We must all be mindful of our language and I’ve said so on the floor of this chamber on many occasions, we must guard against language that is both hurtful and harmful,” he said.
“Over the weekend I let my guard down and for that I am truly sorry.
“I posted a joke and regardless of what my intentions were, it was just inappropriate.
“It was absolutely wrong and fundamentally wrong and therefore it’s important that I stand here and I say to Mr and Mrs Poots that I am sorry for the hurt that I may have caused.
“But I have to say to wider society that my language was wrong at every level and I have to apologise to all of them.”
For those in political leadership that engage in that everyday sexism and think it's a joke, that's just disgusting in itself
Later, during Assembly question time, deputy First Minister Michelle O’Neill said misogyny online was a “huge problem”.
“For those in political leadership that engage in that everyday sexism and think it’s a joke, that’s just disgusting in itself,” she said.
“That’s not political leadership. Political leadership is calling out things whenever it’s wrong and in this case misogyny online is a huge problem.
“In the period that we’ve just come through in the aftermath of the death of Ashling Murphy (teacher murdered in Co Offaly) and the sort of outpouring of grief, but even more than that the anger the fact that this (misogyny) still exists in such a systemic way, for a political leader to be engaged in online what he deems to be jokes, I do not deem to be jokes, I think it’s just incredulous.”
