Chris Brown says attacking Rihanna is the "deepest regret" of his life but he insists the pair have now moved on from the incident and are happier than ever.The 23-year-old singer left the 'Diamonds' hitmaker bruised and battered after physically assaulting her in 2009 but the pair are now back together and he has vowed never to hurt Rihanna again.Chris - was sentenced to five years' probation and six months' community service - told the Daily Mirror newspaper: "Sometimes you row, you fight, with the one you love and things get said, stuff spirals."That night was the deepest regret of my life, the biggest mistake. But she loves me - what can I say? I'm forgiven... but, yes, I worked hard for it."The 'Don't Wake Me Up' singer insists he's a changed person since the attack happened as he's now realised what's important in life.He said: I've learned a lot since that night and I've grown up. I was very young and I took a lot of stuff, fame, for granted."I didn't understand it. The support from those who do know me and the fans, who are incredible, got me through."He also knows some people will never forgive him but he tries not to let that bother him.He added: "People attack me and criticise me, it happens all the time."But they don't know me, and they don't know us. It doesn't bother me any more."Other people can judge us but they don't know anything."