"I was completely and utterly stunned," she told UK newspaper The Mirror, adding that the TV mogul was adamant about not having children during their relationship in the 80s.
"I suppose there has been a certain amount of comfort for me in my not having a child with Simon as he never wanted to have children. That's who he was, you accepted it. Then, to discover that he is going to have a child, only with someone else and they're building this life together." she said.
But the former singer has made peace with the news since.
"All those crazy things were going through my head and it's not fair and it's not pertinent to Simon and Lauren's situation and I don't have a right to feel that way. But I'm being honest," Sinitta explained.
Sinitta added that Cowell was "calm" when he broke the news to her and that he was "concerned about how [she'd] take it."
After a month of silence about getting his friend's wife pregnant, the "X Factor" judge said last Monday he is "happier than I've ever been."
"Oh, my God, it's exciting, and [also] this is going to be a bit of a nightmare now for the next few weeks," Cowell said while visiting "The Ellen DeGeneres Show."
"I can't blame the media, because it was a really juicy story. But there was a lot of stuff that was said about [Silverman] -- that she trapped me and that she's a gold digger -- and it's absolute nonsense. She's a great girl."
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