Ashley Roberts, who is the brother of Bellew’s long-term partner Rachael, was killed while on a family holiday in Cancun where he was celebrating a friend's wedding. It has been reported that he fell from a balcony.
Bellew has agreed to face Haye at the 02 Arena on 17 December in a rematch of their absorbing encounter at the same venue in March but says boxing has been put fully into perspective after the tragic accident in Mexico.
“The last two years of my life everything has gone great,” Bellew said. “Me and my missus sit down and most nights we say, ‘it's going great’ but I say, ‘It’s going that good something has got to go wrong’ and then what happened, happened.
“I suppose that is what has gone wrong.
“It’s horrible. I lost my brother in law and he is gone. Ashley Roberts, 32 years old and he’s gone. It is heart breaking. It puts things into perspective.
“I don't give a f*** about fighting, I fight because I like fighting. I have a lot of pent up anger and frustration in me, and I'm going to unleash it on December 17.”
Bellew, a lifelong Everton fan, sported a red tie in memory of Liverpool supporter Roberts when he and Haye met at a central London hotel for the press conference to formally announce their December clash.
And the former cruiserweight champion of the world says what promises to be a painful 12-week training camp will help get him through his family's grief.
When asked how he has coped, Bellew said: “I just go the gym. When I punch everything else goes away. Then I go home and we are together as a family.
“We don't know the full details yet of what happened. We will find out. It doesn't make sense.
“All I've done is train and gone home and cried for the last three weeks. For these next 12 weeks I'm going to be scared. Every night I will think about making it home. That's my mentality.”
During the set-piece press conference, Haye questioned Bellew's motivation for taking the rematch, having already beaten him once back in March.
That night, Haye suffered a ruptured Achilles tendon in the sixth round and his then-trainer, Shane McGuigan, threw in the towel in the 11th.
Haye claims Bellew became a 'multi-millionaire' as a result of the initial clash so is unsure why the 34-year-old has decided to grant him a second chance at beating him.
But Bellew said: “I will dedicate the fight to Ashley. He has followed me everywhere, Ash loved boxing and he loved me.
“He is a mad Liverpool fan, I don't wear red but I wear red for him today. Ashley was a Liverpool season ticket holder and followed them everywhere so you can imagine the banter we had.
“We went to derby games. It's hard, it's just a tragic accident. The motivation is the same.”
Meanwhile, Haye has confirmed that he will walk away from the sport should he suffer a second successive defeat at the hands of Bellew – and revealed that even a victory might force him to retire.
The 36-year-old Londoner is a former world heavyweight champion and has designs on a huge domestic clash with current IBF and WBA king Anthony Joshua should he get past Bellew.
Haye said: “If I can't beat Tony Bellew, what business have I campaigning for the world heavyweight title? I am not boxing just for the sake of it, for me it is about winning titles and gaining recognition for what I achieve. I have only ever wanted to be the best.
“Even if I was to win on a split decision or I'm legitimately knocked down, then I am not as good as I should be if I want to win the world heavyweight title again.
“You need to be able to deal with fighters like Tony Bellew comfortably. If I can't beat him emphatically, then I can't beat the really big guys and I'll completely forget my world title aspirations.
“I should be able to choose when I knock him out. If I can't then boxing is just something that I used to be good at. If it is not a complete annihilation, then I am not the man that I thought I am. If I win and it's not conclusive, then what is the point in carrying on?”
Haye also revealed that he has had footwear specially made for the contest after the injury sustained in the first fight. It was suggested that his unusual choice of boots, called Vivo Barefoot, may have contributed to the injury.
“I don't know if my footwear was a factor in the first fight,” he added. “It could have just been what I ate that day. Who cares? It is what it was. I've minimised it now.
“I'll be wearing different shoes for this one. I've had footwear specifically made. I tape my ankles now, I put a lace-up thing on it and then I put on my boxing boots which have got a reconstructed support on it. My legs will be fine this time. There is nothing to snap, everything is held in this time so that's it.”