Gates said: "I had several dinners with him, hoping what he said about getting billions of philanthropy for global health through contacts that he had might emerge,
"When it looked like that wasn't a real thing, that relationship ended."
He then added: "But it was a huge mistake to spend time with him, to give him the credibility. There were lots of others in the same situation, but I made a mistake."
During the interview, in which Gates admitted that he regrets having an affair with a Microsoft employee, he also fielded questions about the allegations of toxic workplace culture at the software giant, as well as the Gates Foundation.
In 2019, the company launched an investigation into Gates after an employee came forward to say that she'd had a sexual relationship with him for several years.
Later, Gates' representative admitted that 'there was an affair almost 20 years ago which ended amicably.'
Upon being asked if he had any regrets, he said: "Well, certainly I think everyone does, but it's a time of reflection, and at this point, I need to go forward.
"My work is very important to me,
"Within the family, we'll heal as best we can and learn from what's happened."
Gates described the end of his marriage to Melinda as 'a very sad milestone', adding: "Melinda is a great person and that partnership that we had coming to an end is a source of great personal sadness."
After almost three decades of marriage, Bill and Melinda's divorce was confirmed on Monday. Court documents pertaining to the split said that 'this marriage is irretrievably broken,' and said that both parties 'should be ordered to comply with the terms of the separation contract.'
It is not clear what the terms of the separation contract are exactly, but neither party will be receiving spousal support and Melinda will not change her last name as part of the divorce.
The pair plan to continue working together at their foundation, with a two year trial underway to see if that is possible.
The couple have three adult children together, Phoebe, Rory, and Jennifer.
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