Some of the singer's hardcore followers - known as 'Beliebers' - targeted the British reality star with ''abusive messages'' after it was reported the pair were getting close after spending time together at a recent party.
Now it is said Lauren found the comments and death threats too much to handle and has called time on their ''friendship''.
A source told The Sun newspaper: ''She was getting dozes of vile, abusive messages from his fans, warning her to stay away, accusing her of being a fame-hungry cougar and telling her to 'watch her back'.
''She was even accused of lying about their friendship. It's been really upsetting so she messaged him to say she couldn't continue their friendship. She's gutted but the attention was all too much.''
The former glamour model - best known for appearing on 'The Only Way Is Essex' - was reportedly ''really shocked'' by the comments, and in the beginning she was ''simply excited'' about spending time with the 'Believe' singer.
The insider said: ''Lauren has been really shocked by the level of abuse targeted at her.
''She was totally unprepared and when news broke of their partying together, she was simply excited about seeing Justin again and staying in touch with him.
''For the past 10 days the pair have been direct messaging on Twitter and texting, and things were definitely hotting up.''
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