Tulisa Contostavlos was so paranoid that ex-boyfriend Fazer was cheating on her she had him followed.
The 'Live It Up' singer has confessed she was plagued by insecurity and jealousy when she was in a relationship with her N-Dubz bandmate and by the end of the romance she even had him spied on to see what he was doing when they were apart.
In an extract from her autobiography 'Honest, My Story So Far' - which has been serialised in The Sun newspaper - Tulisa reveals: ''I temporarily moved in with my PA Gareth, telling Fazer I needed a bit of space. Maybe I wanted to give us one last chance. Then one of my friends called me after spotting Fazer and a girl coming out of a nightclub one night, and I asked my friend to follow them.
''Yep, Ghetto Miss Marple was on the case one final time! Sure enough, later that night, my friend sent me a picture of them going into the girl's apartment together, which I sent straight to Fazer.
'''Bingo!' I said. 'Got ya!' Fazer's comeback was something about having been at a part at the girl's place the night before and going back to pick up his phone charger.
''Maybe this was true, and I have no evidence to prove otherwise, but because of the long-running drama between us, and all my paranoia, I just couldn't take the stress any more. I told him we were finished.''
The pop star dumped Fazer - who she has known since they were both 11 after they formed N-Dubz with her cousin Dappy Contostavlos - in January this year with no specific reason given for the separation.
In her book, Tulisa, 24, reveals she called time on the romance after her tried to convince her to give him a second chance following his late night with another girl.
However, 'The X Factor' judge demanded Fazer take a lie detector test to prove he didn't have sex with the girl but he refused.
Explaining what happened the next morning when Fazer turned up at Gareth's door, she says: ''I still didn't believe him, but I didn't have any evidence so I gave him one more lifeline just the same - I'm fair like that. 'Ok then,' I said. 'If you take a lie detector test and you're telling the truth, then I'll give you a chance. Otherwise, we're finished.'
''As I suspected, he wouldn't do the test. He made every excuse under the sun over the next week not to do it. 'Well then we're finished,' I told him.''