Mark Nelson, of Drumchapel, Glasgow, appeared to be a fit and healthy – but he died after suddenly becoming unwell during the night.
His mother Suzanne, 49, said: "A few days before Mark passed away, he mentioned he had been suffering from what he thought was indigestion.
"At his age you would expect it to be something like that – not a heart attack, not at 23.
"I keep expecting him to walk through the door, it doesn't seem real that he has gone forever."
Mark's 50-year-old father, Paul, a pub owner, added: "Mark's death has left a massive gap in our lives.
"It's been a nightmare and we are all devastated. I don't think losing him will ever get easier. "
Mark – who had two sons Mark, 3, and one-year-old Kyle – had started vomiting at home in the early hours of November 17.
His partner Lyndsay, 25, tried to save him after he collapsed.
Suzanne explained: "Mark had been sick and his lips had turned blue. He and Lyndsay decided it was best to call an ambulance.
"But as they made the call, Mark lay down next to Lyndsay on the couch, looked at her and simply said, "I love you, goodbye'.
"Lyndsay tried to revive him, but it was too late."
For days, Mark's family had no explanation for his sudden death, but a post-mortem revealed he had suffered a coronary artery atheroma.
Mark, a football fan who was a Celtic supporter, had studied construction at Clydebank College before going on to work in his dad's pubs. His parents described him as the "life and soul" of the family.
"He was a big family man", Paul said. "Mark was all about his boys and Lyndsay, they were inseparable.
"His family, even his dog, were his life.
"His boys will always know who their dad was, we will never let Mark be forgotten."
His seven brothers, Paul, 31, Stuart, 29, Craig, 28, Gordon, 23, Steven, 22, Kevin, 15, and Aidan, 14, and sister Teri, 27, have all been left devastated by his death.
Suzanne says she has decided to move from the family home in Drumchapel.
She explained: "There are too many memories here, it is too hard. Mark had even been talking about a wee party and getting me a cake for my 50th birthday.
"Losing him has devastated all of us."
The family have been inundated with cards and floral tributes.
Last week, more than 300 family and friends gathered at St Laurence Church in Drumchapel to say a final farewell.
Paul said: "The community has been amazing, they have all pulled together for us.
"Everyone, from the funeral director Alex Black to the local ice-cream van collecting money for British Heart Foundation, has done their bit for us.
"I can't thank them enough. It is a small comfort to know everyone else loved Mark as much as us."
Mark's brothers will now all be tested for any heart conditions or problems.
Paul added: "It is going to be a worry for us for the rest of our lives.
"We need to be sure everyone else is fit and healthy.
"Wee Mark and Kyle will also have to be tested when they are old enough.
"You would never expect a 23-year-old who was fit and healthy to have a heart attack and die.
"I would urge anyone – young and old – who has chest pains to go to the doctor and get them checked out.
"It could be nothing, but it could be something serious.
"And it could save your life – just look at what happened to Mark."
l Anyone who wishes to donate to the British Heart Foundation, can call 0844 8472787 or see the website: www.bhf.org.uk