Pair have drifted apart after dating for 4 years
The actress is believed to have dumped him over the phone last week.
‘They’re still the best of friends but any romantic spark has well and truly gone,’ says a source.
‘It’s really sad but there’s no one else involved.’
Kelly, 28, and LA-based Billy, 42, have been dating on and off for 4 years.
They briefly split earlier this year, before getting back together in May.
‘She’s glad she got back together with him to give things another go,’ the source tells the Daily Mirror.
‘She was desperate to save their relationship but, at the end of the day, it just wasn’t to be.
‘They’re both comfortable with the situation and Kelly seems to be quite looking forward to being a single girl again.’