Andy Murray was at the lowest point of his recovery when he opened up to documentary director Olivia Cappuccini about the trauma he suffered after the Dunblane school massacre.
In a new documentary on his comeback from injury - which will be available on Amazon Prime Video from November 29 - the former world number one opens up on the 1996 incident.
He and his brother Jamie were present at Dunblane Primary School where Thomas Hamilton killed 16 children and a teacher before shooting himself.
During the premiere of 'Andy Murray: Resurfacing', guests were able to hear a voice note that the Scot sent to Cappuccini after she had repeatedly asked why tennis is so important.
The two-time Wimbledon champion went on to explain how it has acted as an escape from a difficult childhood, which included the Dunblane massacre, and in a Q&A session he went into further detail about the voice note from December 2018 - just before his emotional Australian Open exit.
"When I was chatting to Liv at times during it, she'd asked me why tennis was important to me," Murray told an audience at Curzon Bloomsbury.
"I'd say: 'I love tennis and it's been a big part of my life but there is a bit more to it than that, but I don't want to talk about it'.
"Then over time I felt that I was at my lowest point actually in December at the end of 2018 when I sent the voice note.
"I messaged her and said: 'Look I don't want to do this, I'm quite embarrassed talking about it' and I sent it and realised when I sent it that it was quite emotional.
"And I'd said things I hadn't really spoken to many people about, if any, but it was quite a difficult period for me.
"I do remember when I went over to Barcelona at 15 to train, that was the couple of years where I moved away from home and I loved it.
"That is the period in time, if I could go back in time, I would go back to because I felt freedom and I met new people and new friends."
The documentary charts Murray's journey from his first hip surgery in January 2018 through to his second hip operation a year later, with footage showing the resurfacing procedure.
Emotional and raw throughout, it details his comeback from the brink of retirement to playing pain-free again at Wimbledon, but it is the voice note to Cappuccini which is most revealing.
Murray told the film-maker: "You asked me a while ago why tennis was important to me. I had the thing that happened at Dunblane, when I was around nine.
"I am sure for all the kids there it would be difficult for different reasons. The fact we knew the guy, we went to his kids' club, he had been in our car, we had driven and dropped him off at train stations and things.
"Within 12 months of that happening, our parents got divorced. It was a difficult time. To see that and not quite understand what is going on.
"And then six to 12 months after that, my brother also moved away from home. He went away to train to play tennis. We obviously used to do everything together. When he moved away that was also quite hard for me.
"Around that time and after that, for a year or so, I had lots of anxiety that came out when I was playing tennis. When I was competing I would get really bad breathing problems.
"My feeling towards tennis is that it's an escape for me in some ways because all of these things are stuff that I have bottled up. I don't know because we don't talk about these things.
They are not things that are discussed.
"The way that I am, on the tennis court, I show some positive things about my personality and I also show the bad things and things I really hate. Tennis allows me to be that child, that has all of these questions, and that's why tennis is important to me."
Andy Murray: Resurfacing will launch exclusively on Amazon Prime on Friday 29 November.