In an interview with WSJ magazine, Taylor said: "I knew from when I met her I would always have her back. In my life, I have the ability to forgive people who have hurt me. But I don't know if I can forgive someone who hurts her."

Selena and Taylor, 30, have been close since their respective romances with Nick and Joe Jonas in 2008, and the 'Look At Her Now' singer gushed over their "instant" connection.

The 27-year-old singer and actress told the publication: "We clicked instantly and, man, that was my girl. We both went through s**t at the same time. She taught me a lot about how I should be treated at a young age."

After recently taking time away from the spotlight to work on both her physical and mental health, Selena is gearing up to release her new album 'Rare', which will mark her first in four years.

And Taylor couldn't be more proud of her pal.

She said: "This is the first time I've heard her truly channel the details of her emotional experience. I just thought, 'Wow, she's finally allowing herself to let other people know things aren't always OK.'

"You can be vulnerable and lonely and independent and strong and brave and scared all at once."

Whilst Selena added: "I remember Taylor said when I played her some of the new songs, 'I feel like I'm seeing who you were before this.' That makes me happy. I like feeling like that girl again."