The footage was made available to purchase on a website last month, before lawyers for the star took action, obtaining an injunction to prevent further publication.
The 23-year-old confirmed the authenticity of the tape in a video statement, in which she blamed ex-boyfriend MC Ultra for being behind the leak.
Admitting that she had been left "devastated", Contostavlos told The Guardian: "I slept on the bathroom floor for seven days... I just wouldn't go out of the house. Couldn't sleep. Didn't really want to eat anything. But I snapped out of it.
"I knew what I was doing. I knew in my head that I was depressed; I knew why I was depressed. It was all logical. I didn't want to smile. I didn't want to be happy. It was like a level of mourning, do you know what I mean?"
She continued: "I needed to have my tears and tantrums, my bad moods, and get myself into a state to come back out of it. And I literally just woke up one morning, as happy as Larry, put on my best dress, make-up, full hair, 'OK, I'm going out'."
The 'Young' singer admitted that she felt attempting to "sweep it under the carpet" had made the whole affair "more seedy than it was", prompting her to cut off communication while she filmed her own personal statement.
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"I guarantee if everyone else out there had a camera practically shoved up their arse on a day-to-day basis, in their face, that a lot worse stuff would come out," she said, hitting back at those who have publicly criticised her.
"There are probably girls out there who have done a million times worse with their boyfriend, and are probably going to go out tonight and get laid with a random bloke they've just met, whereas I'll meet a bloke and make him wait six dates before he even gets a shag. But because of some footage, people make assumptions about the sort of character I am."
Taking the opportunity to dismiss claims that the leak had been a publicity stunt, she told the newspaper that she had not been "physically" able to watch the footage.
"But from what I've heard, I'd make sure I was a lot sexier, and probably not 19 years old, because that's a little bit pervy," she said. "People seem to be forgetting that I'm 19 in it, which is quite wrong. Everything I've spent my whole career building up and representing - I wouldn't even do a bikini shoot with FHM, so why would I release a tape? Why am I spending thousands of pounds in legal costs to stop it coming out?"
Confessing that she does not "really like being vulnerable", Contostavlos said that it would be ideal if the tabloids could stop writing about her, while she still gets "paid the same amount I do".
"But I suppose it comes with the other things," she added. "If I'm not in the public eye, and then I'm not wanted, and I'm not getting endorsements, I'm not being talked about, my records aren't going to be bought. I just wish they wouldn't lie as much."
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Watch the video for Tulisa's debut solo single 'Young' below: