The band's frontwoman admitted that she fell in with a bad crowd during a troubled childhood, before starting a relationship with an abusive older man.
"I had my first proper boyfriend as a teenager," The One Liner reports her saying.
"We were sexually active and I was staying over at his house. But it was a bad relationship. I had lied about my age and he was older than me. He was really handsome and everyone fancied him but he was violent and abusive towards me.
"It was mad because on the streets I was powerful and tough. But as a female in a relationship I was weak as hell. He just broke me down into nothing and made me feel like crap.
"He'd tell me I was ugly and lock me in the bathroom while he went out. I don't blame him - he had a very tough upbringing - but eventually he left me for another girl.
The singer, real name Tula Contostavlos, then developed anorexia and tried to commit suicide due to her depression.
"I was so devastated that I stopped eating and dropped a stone and a half, down to seven stone. That's when my self-harming got really bad and I even took it further twice by trying to kill myself.
"My mum had loads of pills in her cupboard so I went in there and grabbed a bottle of whatever I could see. I ended up necking a load then becoming really sick, throwing up."
She continued: "Another time I slashed my wrists and they started bleeding really badly, which panicked me as I realised what I was doing to myself.
"I remember sitting there holding a towel over it and crying, thinking 'What am I doing?'"