Taylor Swift says her feud with Scott Borchetta over the sale of Big Machine records ''redefined betrayal'' for her.

The 29-year-old singer was left feeling ''grossed out'' earlier this year when her former record label boss Scott sold Big Machine records to Scooter Braun - whom Taylor has accused of bullying her - and with it handed Scooter her back catalogue of master recordings, which he now has the rights to.

And now, Taylor has explained that she had originally believed Scott ''looked at [her] as the daughter he never had'', and so found his betrayal even more painful because it ''felt like it was family''.

Speaking about the sale, she said: ''A lot of the best things I ever did creatively were things that I had to really fight - and I mean aggressively fight - to have happen. But, you know, I'm not like him, making crazy, petty accusations about the past.

''When you have a business relationship with someone for 15 years, there are going to be a lot of ups and a lot of downs. But I truly, legitimately thought he looked at me as the daughter he never had. And so even though we had a lot of really bad times and creative differences, I was going to hang my hat on the good stuff. I wanted to be friends with him.

''I thought I knew what betrayal felt like, but this stuff that happened with him was a redefinition of betrayal for me, just because it felt like it was family. To go from feeling like you're being looked at as a daughter to this grotesque feeling of 'Oh, I was actually his prized calf that he was fattening up to sell to the slaughterhouse that would pay the most.' ''

The 'ME!' hitmaker says the news of the sale - which she previously insisted she discovered at the same time as the public - came as a ''really hard shock'' to her, and has slammed both Scott and Scooter for being ''sneaky''.

She added: ''The fact that those two are in business together after the things he said about Scooter Braun - it's really hard to shock me. And this was utterly shocking. These are two very rich, very powerful men, using $300 million of other people's money to purchase, like, the most feminine body of work. And then they're standing in a wood-panel bar doing a tacky photo shoot, raising a glass of scotch to themselves. Because they pulled one over on me and got this done so sneakily that I didn't even see it coming. And I couldn't say anything about it.''

Whilst Taylor is using her voice to speak out against the decision to sell off her master recordings, she admits she would have been ''too afraid to speak up'' three years ago, before heading out on her ''emotional'' 'Reputation' tour.

The 'Bad Blood' singer told Rolling Stone magazine: ''It was sometime on the 'Reputation' tour, which was the most transformative emotional experience of my career. That tour put me in the healthiest, most balanced place I've ever been. After that tour, bad stuff can happen to me, but it doesn't level me anymore.

''The stuff that happened a couple of months ago with Scott would have levelled me three years ago and silenced me. I would have been too afraid to speak up. Something about that tour made me disengage from some part of public perception I used to hang my entire identity on, which I now know is incredibly unhealthy.''