The 34-year-old singer, who is taking part in the ITV2 show with bandmates Lee, 29, Anthony 31 and Simon 34, spoke about his struggle with accepting his sexuality at the height of Blue's fame.
'If anybody ever used to say anything about me... I would get this panic inside of me'
James admitted to being bisexual in an interview with a British newpaper in 2009, just before Blue regrouped.
In the interview James disclosed that he had loving relationships with both men and women, and was happy to be bisexual.
Last night’s episode, which sees former nineties and noughties bands regroup to take part in a Big Reunion tour kicking off in May, the Sooner Or Later singer revealed:
“I wanted to still be kind of known as ‘Duncan James from Blue, the heartthrob’. If anybody ever used to say anything about me – ‘I think he's gay’ - I would get this panic inside me.”
He also revealed a secret relationship he had whilst in the band with one of the male backing dancers.
“I actually really liked him and I couldn't tell anybody. I used to ring him up paranoid, ‘Have you told anybody? Have you told anybody?’.”
He admitted that during the relationship he was still having sexual relationships with women, holding on to his lothario title, and has previously had flings with Geri Halliwell and Tara Palmer Tomkinson.
Reminiscing over the relationship with his backing dancer, Duncan added:
“I broke his heart to the point where he couldn't be with me in that way any more and ended it.”