The model, 33, was horrified when she found messages to other women on the rugby player's mobile phone last weekend, according to The Sun.
The former Big Breakfast presenter's discovery came just days after they returned from holiday in Turkey.
It's over... again: Kelly Brook and Danny Cipriani, pictured in London in June, have reportedly split up for the second time
The Sun claims Danny, was even sending sexy messages to other women while Kelly nursed him back to health after he was hit by a bus in April.
When Kelly found the messages, she threw Danny out of her London home and has since deleted all recent photos of him from her Instagram page.
Sales manager Stacey Simcox, from Birmingham, claims she was bombarded with sexy messages and photos from Danny after meeting him eight months ago.
Stacey told the paper: 'He'd send me filthy messages about what he wanted to do to me and begging to meet up for sex.
The Sun claims Danny, was even sending sexy messages to other women while Kelly nursed him back to health after he was hit by a bus in April.
When Kelly found the messages, she threw Danny out of her London home and has since deleted all recent photos of him from her Instagram page.
Sales manager Stacey Simcox, from Birmingham, claims she was bombarded with sexy messages and photos from Danny after meeting him eight months ago.
Stacey told the paper: 'He'd send me filthy messages about what he wanted to do to me and begging to meet up for sex.
Unfaithful? Kelly and Danny in London on June 29 - the last time they were photographed in public'It got progressively more explicit and I just thought, "What a rat."'
Stacey said she refused Danny's requests to meet up, even receiving an invitation as recently as July 27 - the day he flew to Bodrum with his famous girlfriend.
A friend told the paper: 'Danny is absolutely devastated. He just can't believe what he's done - he just wants Kelly back.'
While Kelly hasn't directly referenced the split on her Twitter, she did post a saying on her Instagram on Sunday, reading: 'Some people come into your life as blessings, others come into your life as lessons.'
Calm before the storm: Kelly posted this photo of the couple in Turkey just over a week ago - which has since been deleted
Happy together: Danny posted a photo of Kelly with their friend Kasia Wolejnio on holiday in Turkey on July 29Kelly started dating Danny - who she previously dated for 22 months until June 2010 - in January this year, just weeks after she split from his former England teammate Thom Evans.
When Kelly and Thom announced their split, she vehemently denied it had anything to do with her spending time with her ex Danny.
Meanwhile, retired rugby player Thom has also moved on and is dating former 90210 actress Jessica Lowndes.
In May, Kelly was involved in a war of words on Twitter with nemesis Katie Price - who briefly dated Danny in October 2011 - with the mother-of-three claiming Danny will 'never be faithful'.
MailOnline has contacted Kelly and Danny's representatives for comment.
