The 'So Macho' singer, who is godmother to his newborn son, Eric, his first child with girlfriend, Lauren Silverman, is happy to be friends with the music mogul.
She told OK! Magazine: ''The whole are-we-or-aren't-we thing with Simon and I ... Being a bit stuck or hung-up on each other, but not being able to fully commit to each other and equally not being able to fully move on ... In recent times we've finally been able to do that and him having a baby with Lauren certainly stops the yo-yo situation forever.''
The brunette beauty thinks Simon, 54, has met his match with Lauren, 36, and feels they ''deserve to be together'' and be happy as a family with Eric, who was born on Valentine's Day (14.02.14).
Sinitta said: ''Lauren has made my best friend extremely happy and he's finally found the woman he truly loves.''
The 45-year-old singer, who dated Simon in the 1980s, admitted the TV mogul hasn't always been able to be a ''faithful boyfriend'' until now, but she insists he has been a ''faithful friend'' and she has a close bond with his mum Julie.
She said: ''Simon and I have good times together. We care for each other's families. His mum's like my mother. I've known her since I was a teenager, we're old family friends.''
Sinitta also addressed rumours that Simon, who is godfather to her children, gives her a wage, claiming she earns her own money but says he is generous when it comes to her son Zac, seven, and daughter Magdalena, eight.
She said: ''When I was mentoring [on 'The X Factor'] he paid me the going rate. As godfather he pays towards my children's school fees and he buys us lovely birthday and Christmas presents. He's a generous friend but I earn my own money.''
The BBC drama starring Aidan Turner returns to BBC One on September 4th.