has opened up about the way that her spell in rehab has changed her approach to her friends. Speaking in an intimate new interview with Company magazine, the pop star and The X Factor USA judge said that her troubles had helped her realise who her true friends are. She said: "A couple of months before I went to rehab, I had a birthday party and there were a couple of hundred people there. It was full of people who I considered my closest friends. "When I turned my phone on after being in rehab for three months, I expected lots of text messages and phone calls. I had four texts. That was a wake-up call. I have severe trust issues but I try not be jaded."And the 20-year-old also revealed that she likes to socialise with people who exist outside of the showbiz bubble. "I don't have loads of friends. I used to, but then I realised, do any of them actually care? Now I have people who, if I break my leg in the middle of the night, they'll come to the hospital with me. Or they'll answer the phone at 4am if I need them. "Most of my friends are not in the industry. I don't like that lifestyle, the paparazzi, going to Hollywood places. I stick to my neighbourhood and to my closest friendships."