The girlfriend of Eamonn Magee jnr last night said her "life has been ripped apart" following his brutal murder in west Belfast.
Courtney Ward was speaking as detectives continued to question a 32-year-old man over the killing.
The promising young boxer was stabbed in the early hours of Saturday after stepping outside her home at Summerhill Park in Twinbrook.
Ms Ward told the Irish News how he had arrived before 9pm that night to enjoy an evening in together.
"Me and him were having a few drinks in my living room. We were laughing and joking and dancing away in my living room and listening to music. It was just the two of us," she said.
The 23-year-old, a mother of three young children from a previous relationship, said at about 1.30am they ordered a pizza but phoned again later when it did not arrive.
She then went upstairs to the bathroom while Mr Magee (22) went outside to check for the delivery.
"I heard screaming and a big cry and I heard voices but I didn't recognise the voices it happened so quickly," she said.
Ms Ward said she went outside and saw two neighbours with Mr Magee who was lying on the ground.
"I was traumatised. I was in pure shock. Everything was going through my head. 'Is this for real?' My whole world just crumbled and I literally just collapsed to the ground."
Residents tried in vain to save the boxer, who succumbed to his injuries shortly after arriving at the Royal Victoria Hospital.
Police have described the stabbing as "vicious".
Detectives believe the young engineering student's killer lay in wait outside Ms Ward's home.
The knife used in the killing is thought to have been stolen from a property nearby.
The arrested man is understood to be a Turkish national who works in a Belfast night spot.
He was arrested by police at commercial premises in Dunmurry following the stabbing.
On Sunday night police were granted a court extension of 28 hours to continue questioning him.
Ms Ward said she met Mr Magee earlier this year when she attended boxercise classes he held in a local gym.
"I went to his classes and he was a personal trainer as well, and that's how I met him," she said.
"I was friends with Eamonn since March and then we started meeting each other from the end of March, and our relationship got more serious on April 27. And from then he stayed in my house every single night.
"We were with each other all the time. There wasn't one day went by that we weren't with each other."
She said she felt guilty over the death.
"I just feel like it's my fault. I just feel like it's my fault that Eamonn was in my house," she said.
Paying tribute to her boyfriend, Ms Ward described him as very kind and caring with so much ahead of him.
"Me and Eamonn loved each other so much. We were so happy to be in each other's company and, I know this may sound really stupid but we were planning to spend our lives together. That's how much we loved each other," she said.
"There was no one else he wanted and there was no one else I wanted. We were really good friends as well and we told each other everything.
"I'm going to miss him terribly. Words can't explain how much I'm going to miss him.
"I am absolutely heartbroken and devastated at what's happened to him. My life is ripped apart."
Mr Magee was a former pupil of St Mary's CBS in west Belfast and had just finished the first year of an engineering degree at Ulster University.
His parents have spoken of their devastation at his death, with his father saying he was a "pleasure to rear".
Tributes have also been paid across the boxing world, where the 22-year-old was due to fight in his third professional bout in August.
Former world champions Barry McGuigan, Ricky Hatton and Brian Magee and current holder Carl Frampton have been among those to express their condolences.
