we just want to be together all the time.
The couple, who revealed their news in an interview with a UK magazine, were on holiday in the Carribean when Matthew got down on one knee.
‘We were on a balcony that overlooks the ocean. It was just beautiful. She said yes! And then she smiled for the rest of the night!’ said Matthew.
Kelly, who met Matthew at Kate Moss's wedding in 2011, said: ‘I've never felt this close to another human being, ever. People say we're co-dependent but we just want to be together all the time.’
The 28 year-old TV presenter also revealed she had designed her own engagement ring to look like one of rocker dad Ozzy’s jewels.
‘I designed it to look like an earring that my father wore,’ she said.
‘I used to hold my finger up to his ear when I was little and say, “I want a ring like that.” Now I have one.'
I knew she was “The One” pretty early on
Matthew – who told the magazine he ‘knew [Kelly] was “The One” pretty early on’ – moved from New York to Los Angeles to be with Kelly a year into their relationship.
‘Matthew made the biggest sacrifice anyone's ever made for me, to move away from everything that he knew to be with me in LA,’ Kelly said.
‘Long-distance relationships often don't work out. We'd dated for a year and knew we wanted to be together.’
Kelly - who was previously engaged to Luke Worrall in 2009 before spliting a year later – said: ‘Matthew has broken down every one of my walls. There's nothing I wouldn't do in front of him.’
In the interview, Kelly also addressed recent reports that her parents were set to divorce after Ozzy confessed a drug and alcohol abuse relapse earlier this year.
She said: ‘As if my mother would ever leave my father! They were never getting divorced, they were separated. As mum said: “You're drinking again and I'm not going to talk to you,' like any normal person would do.
‘Then Dad got himself together. He's been under a lot of pressure – the new Black Sabbath album, my brother's MS... things can get too much for addicts to handle.’
Kelly’s brother Jack was diagnosed with multiple sclerosis in 2012 after he lost 60 per cent vision in his right eye.