The 24-year-old first hooked up with the Goth rocker when she was 19 and although they called off their engagement last year, she doesn't believe it was a waste of time.
'Just because a relationship ends, it doesn't mean that it failed,' the Ides Of March actress told The Independent.
'I don't think I would be the person I am today without him. He is inspiring. The timing was right and I felt a door was open to me to really explore, express myself and take risks.'
Now believed to be dating Billy Elliot star Jamie Bell, the openly bisexual star revealed that she has always felt an attraction to both sexes.
'It's funny when you suddenly realise you bought into a certain idea for so long. You're just raised with a certain idea of what a girl is supposed to be and what a boy is supposed to be. That is not necessarily real. It's just what you've been taught,' she said.
'I've always felt that way [bisexual] for as long as I can remember. I truly feel like you're just born a certain way and I feel the more people are honest about something as human as sexuality, the more it will stop being a big deal.'