The singer says the music mogul insisted he never wanted children when they were together so the news that he was going to become a dad for the first time left her 'stunned'.
Speaking about the moment she was told the news, Sinitta told The Mirror: “I was completely and utterly stunned. I was in such a daze, to the point where I wondered if I was dreaming it.
“He sounded… odd, calm, strange, which threw me. I don’t mind admitting all sorts of emotions were running around inside me.
“He was concerned about how I’d take it, which, on reflection, he didn’t need to be. He didn’t owe me that consideration.”
And Sinitta, who first dated Cowell in the 80s admitted she felt betrayed by her former loverm, saying: "I didn’t realise he and Lauren were falling in love and, when I found out, I will admit I was taken aback and did feel a sense of betrayal.”
Last week Simon gave the biggest hint yet that he might be ready to get married and settle down with New York socialite, Lauren.
“I’m not ruling anything out in the future," he told The Sun. "If you asked me a year ago, at my age am I going to have a baby, I probably would have said ‘no’ so you’ve just got to take each day as it comes now. Whatever feels right you should do.’’