Colin Craig has told the High Court in Auckland that he will present hundreds of text messages between him and Rachel MacGregor.
The former Conservative Party leader is suing his former press secretary for defamation. MacGregor has a counterclaim against Craig for defamation.
MacGregor was hired by Craig prior to the 2011 and resigned just days before the 2014 election.
She filed a sexual harassment complaint against Craig, and the pair reached an out of court settlement which included a confidentiality agreement.
The Human Rights Tribunal ordered Craig to pay MacGregor $120,000 after it ruled that he had breached the agreement by talking about her in media interviews.
Craig told the court that the pair had a 'close affectionate' working relationship and a personal friendship.
"We shared similar interests and values, including a Christian faith," he said.
Craig said they would often work 50, 60 hour weeks and would correspond positively with each other through hand written letters and text messages.
Craig said hundreds, possibly thousands of text between the pair will show the 'true nature of the relationship'.
Craig said MacGregor had a very different view of their relationship and that led to the allegations that he had sexually harassed her.
After the 2011 election result, Craig claims he and MacGregor went back to the Conservative party headquarters where they kissed and 'things progressed slightly further'.
"It will be my evidence I stopped that, and I went home."
He said they agreed it regretted and they worked to put boundaries in place to ensure it didn't happen again.
The trial has been set down for two weeks.
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