Demi Moore reportedly feels ''sick to her stomach'' over claims her estranged husband Ashton Kutcher is dating Rihanna.

The troubled 'Ghost' actress - who recently completed a stint in rehab for a reported eating disorder and addiction - is said to be heartbroken after Rihanna was photographed making a late night visit to Ashton's home last week

A source said: ''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'.

''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.

''She's in a terrible way but, at the end of the day, Ashton is a single man and free to do whatever he likes.''

The pair split last November following allegations the 'Two and a Half Men' actor had been unfaithful on the weekend of their sixth wedding anniversary, and according to a second report, she is struggling to come to terms with how quickly he has moved on.

A source told Closer magazine: ''Demi can't believe Ashton would do this.

''She's really hurt by the rumours and feels humiliated he's being linked to other celebrities just a few weeks after she got out of rehab.

''She feels it cheapens their marriage even further.''