London, Mar 29 (IANS): Actress Demi Moore is reportedly heartbroken after learning that her estranged husband Ashton Kutcher is dating singer Rihanna. But Rihanna says she is "single" and "happy".

Moore, 49, who has completed a stint in a rehab for a reported eating disorder and addiction, was devastated when she saw a picture of Rihanna making a late night visit to Kutcher's home.

"Demi is constantly keeping tabs on Ashton. So when these pictures came up, she was understandably devastated. Demi's convinced something happened between them and said she felt 'sick to her stomach'," femalefirst.co.uk quoted a source as saying.

"Demi's been acting crazy ever since, trying to find out information about the pair. Demi is in such a fragile state, even the idea of them together has affected her quite badly," the source added.

But pop star Rihanna is denying any romantic link up with Kutcher.

The 24-year-old got annoyed when a journalist quizzed her about the rumoured romance, reports contactmusic.com.

She replied: "Wow, how disappointing was that question? I'm happy and I'm single, if that's what you're really asking."