It is more than three decades since the June day that OJ Simpson stood, somber and holding his children's hands, at the edge of Nicole Brown Simpson's grave as she was laid to rest. 

No one was ever brought to justice for her brutal murder. Slain on June 12, 1994, she was left to bleed out on her doorstep in Brentwood, Los Angeles, alongside her friend Ron Goldman.

But today, Joseph Perrulli, who dated her after she had separated from OJ, is in little doubt that had their relationship continued, Ron's fate would have been his own.

For the first time, he has revealed the intimate details of their relationship - including a trove of love letters and notes that he kept hidden in a briefcase for decades until he was ready to face reading them again. 

And he says he feels lucky to be alive, saying that a jealous OJ relentlessly stalked the couple during their affair - spying on them kissing on her sofa and even following them around Los Angeles in his car. His final, sinister interaction with OJ still sends shivers down his spine.

His 'detachment was so chilling,' says Perrulli, 'I wondered if he even had a pulse.' 

Writing in his new memoir Forgotten Briefcase, Perrulli says he first met Nicole in the spring of 1989 at a lunch with their mutual friend, Kris Jenner. Nicole was still married to OJ at the time and Kris to her first husband, Robert Kardashian.

He said Nicole looked extremely depressed and claims Jenner told him on the drive home that she was being beaten by her sports icon-turned-actor husband.

The two didn't reconnect until the springtime three years later and soon started dating - by which time the beautiful socialite had separated from OJ and begun divorce proceedings. Kris had married Caitlyn Jenner - then Bruce - one month after divorcing Kardashian in 1991. 

Perrulli describes a chilling prediction he received from Jenner who told him: 'Nicole's a great girl. An incredible mother too. And she isn't caught up in all that crazy Beverly Hills crap, that's for sure. Her only problem is OJ.'

When Perrulli remarked that the couple had split up, he writes that Jenner fixed him with a stare and said: 'OJ will always be her problem.'

It wasn't long, however, before Perrulli and Nicole were inseparable - embarking on what he describes as a passionate love affair.

The first sign of trouble came the first night he visited her at her new home in Brentwood, which she was renting following her separation.

'The only thing I don't like about this house are these windows,' he quotes her as saying. 'I love the natural light they bring in, they don't give much privacy, even with the shades drawn.'

Her fears were to be proven well-founded.

A few days later, she called Perrulli in tears, telling him a neighbor had seen OJ 'creeping around' that night, 'peeking into my windows.'

He remembered that night only too well. When he'd left, he had sensed a presence on the doorstep seconds before - one that had left a lingering, distinctive scent behind.

Both OJ and Nicole wore the same Paco Rabanne fragrance.

'I couldn't speak,' he writes after learning about the stalking incident. 'The thought of her abuser leering at us through her living-room windows made my skin crawl.

'And then it dawned on me. The eerie feeling I'd had when I left her house hadn't been a figment of my imagination after all - it had been OJ. He had been there all along.'

Friends warned him off the relationship, he writes.

One called and laid it on the line: 'I hate to be a buzzkill, but have you lost your frickin' mind?

'In case you haven't heard, it's a well-known fact around town that OJ has abused Nicole, and I don't just mean verbally. He beat her.'

His friend asked him: 'Are you willing to get involved in such a volatile situation? And by doing so, potentially make things worse for her?'

Freaked out, Perrulli says he broke things off but their romance was rekindled soon after, during a romantic trip to Cabo San Lucas, Mexico, with the Jenners.

Within weeks, Nicole was telling her new man that she loved him - he claims they even discussed moving to Mexico together to open a restaurant.

The couple exchanged their favorite books, and sent each other sweet love notes expressing how deeply they felt about each other.

In one, Nicole wrote: 'I just want to say that I really had a great time last night. I know you were a little nervous about it all, but I'm glad we got to spend some time together. 

'I'm just a little perplexed that I still have such a love for you... You're very special to me, and I just want you to know that.'

In another: 'I want to thank you for showing me that I'm still capable of caring so deeply for someone. 

'It was a feeling I thought was gone forever. I never thought I could feel like this about anyone again.'

She even told her former husband she was in love with someone else.

'I told you I was going to live my life openly and honestly, and that's what I'm doing,' Perrulli reports her as saying. 'I told him the truth, before he tries to put any more effort into saving our marriage. Before he tries to come between us.'

He writes: 'I remained tongue-tied, while my mind was racing ahead to another stalking incident - or something far worse.'

It didn't take long for his fears to be realized.

The couple went on a run one morning, along with one of Nicole's friends called Cora.

'This being an early Saturday morning, there were no other runners on the meridian,' he writes.

'The traffic on the boulevard was oddly quiet too; even as we approached the always-bustling Country Mart at 26th Street, there wasn't a soul within sight, other than a man standing on the corner near the entrance holding hands with two small children.

'But as we got closer to him, I realized he was staring directly at us, in anticipation of our approach - as if he knew the exact moment we would be passing by.

'Then his face came into focus. It was OJ.' The couple's two children were with him.

Nicole was convinced he had followed them and insisted Perrulli run on ahead while she and Cora confronted him.

'Since we were jogging along the south side of the meridian, I was positioned close enough for OJ to steady his gaze on me - and this he did, while totally ignoring Nicole who had already approached the children.

'I could feel his glare pulling me in as I continued to run by. I had no choice but to return his stare, and the moment our eyes locked, a chill ran down my spine.

'I saw someone else behind his ominous glare... I saw the monster from Nicole's nightmare. And the monster was making it perfectly clear to me that he had no intention of ever going away - he was and always would be Nicole's problem.'

On another occasion, he was meeting Nicole's extended family in Laguna Beach when it was reported that OJ had turned up in town unexpectedly, so they cut their trip short.

Ultimately, he writes, this constant fear of when OJ's dark presence might appear was what caused him to call off their relationship.

He heard briefly from her over the course of the next few months - she called him in October 1992 to let him know her divorce was finally settled. But he didn't see her again until the Jenners' famous Christmas Eve party in 1993.

Unbeknownst to him, Nicole had briefly reunited with OJ and the pair turned up together.

The hosts were mortified, he writes, and Nicole could barely look at him. But his most memorable encounter from that evening came when OJ approached him at the bar.

'I was suddenly overtaken by an achingly familiar scent. It was Nicole's cologne. I was certain of it.

'But when I turned around, I suddenly found OJ standing in front of me, blocking my egress from the bar. My only option was to acknowledge him.

'"Hi, OJ," I said. "You're looking well."

'Why I said that I had no idea. He didn't look well at all; in fact, he looked completely unhinged. Microscopic beads of sweat were pulsating on his forehead, and he was gripping his empty champagne flute so tightly, I thought it might shatter in his hand.

'As he reached toward the bar to set the glass down, he turned and fixed me with a cold, emotionless stare.'

'"It's only an illusion," he replied, with a detachment that was so chilling I wondered if he even had a pulse.' 

He never saw Nicole again. Six months later, a friend called to tell him the awful news: his former lover had been savagely murdered on her doorstep, along with her friend Ron Goldman.

In his shock, he couldn't help but think he'd had a lucky escape.

'I hate to say I told you so,' said a friend over the phone - the one who had warned him off in the first place.

'It could have been you lying dead with her. That same thing could have happened at any given moment you guys were together at her house. Always remember that.

'In many ways, you're a walking Ron Goldman.'

The Forgotten Briefcase: The world knows her name. Few really knew her by Joseph Perrulli is out now.