The 27-year-old singer took to Twitter to post an angry rant about the ''sick'' blogger after one of her fans informed her he was being shown around an apartment inside her New York building, and she also claimed he has been ''harassing'' her.
She wrote: ''STAY AWAY FROM ME + MY FAMILY YOU ARE SICK TRYING TO RENT AN APARTMENT IN MY BUILDING TO STALK ME. LEAVE ME ALONE!!!
''DO I NEED TO BE SHOT IT IN THE HEAD FOR PEOPLE TO UNDERSTAND THAT HIM AND EVERYONE ELSE THAT HARASSES ME HAS GONE TOO FAR? I'M A HUMAN BEING. (sic)''
However, Perez - who has a six-month-old son Mario Armando Lavandeira III - hit back at the 'Born This Way' hitmaker by posting a 352-word blog post entitled 'A Statement On LadyGaGa's Lies (sic)', in which he denied stalking her and insisted he wasn't aware she lived in the same apartment block.
He wrote: ''I learned only after the fact that Lady GaGa lives in one of the buildings we looked at, and she was across the country in Los Angeles when I viewed that building.
''After a day of innocent house-hunting, I am devastated and my heart hurts that my former very good friend, a person I used to call my ''wifey'' and traveled the world with, is making very public and very untrue allegations about me on Twitter.
''While it is still too painful for me to go into detail about why I chose to no longer make her a part of my life, I will say that I am a critic and not a ''stalker''.
''Any allegation that I am stalking her, based on a day of house hunting with my baby boy and my mother, is utterly false, defamatory and now appears to be putting me and my family in danger. (sic)''
Shortly before the feud erupted, Gaga took to Twitter to reveal Perez had poked fun at her when she was left wheelchair-bound after suffering a labral tear on her right hip earlier this year.
She wrote: ''Still have the text Perez sent me of me in a wheelchair w the words KARMA written across + Madonna pointing a gun at me. Day of my accident (sic)''
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