In two weeks and four days, I turn 36 – but I’m not sure what to make of it.

Back in 1993, sixteen-year-old me had very firm ideas about what “middle-aged” me was going to be like projected 20 years into the future.

“I’m not going to be a lonely old spinster with only a cat for company” and “I’m going to crack France, Germany, Spain, Italy and then Eastern Europe” were two of the gems I wrote in blue Parker cartridge ink on October 25, 1993.

The ambitious perfectionist in me meant I was obsessed with seizing every moment and, even though, I’d only done a total of two weeks’ work experience on the Echo, I was already planning my domination of the world’s media.

But, because I was a hormonal teenager, I also spent a good deal of time speculating about my future love affairs, predicting (accurately, as it turns out) that “I’ll speak lots of languages having had affairs with lots of gorgeous, foreign men as I move around Europe (the world?) for work.”

Many of the entries, which started on July 4, 1992 and go up to the present day, are tear-jerkingly hilarious to the point that my friend, S., and I had to cut short a phone call this week because we were laughing so hard that we could barely talk.

“Oh my goodness, I’d forgotten all about that,” he said, as I read out an excerpt from the beginning of 1996 when I almost got thrown out of university for writing a controversial article in the student magazine. But the discovery of my diaries is more than just a nostalgic flashback to my past.

Matt’s suicide threw my life off course in a way that I – and I suspect he – could never have predicted.

As the ball of grief, shock and numbness knocked me sideways, I went from being the confident, ballsy, go-getter to someone whom I no longer recognised.

The person who stared back at me in the mirror or in a shop window was a stranger: the dull, thin hair clinging flatly to my scalp, the eruption of angry, red spots all over my face and the dark shadows under my eyes that bore witness to months of violent nightmares and broken sleep meant I was nothing like the bright-eyed, make-up free person I was before.

And, in terms of personality, I no longer had one. Because that’s the thing with suicide. You suddenly feel worthless because you weren’t good enough for the person that chose to end their life.

Then, when friends who you thought would be there for life suddenly don’t want to know and ignore you when you need them most, it compounds the feelings of insecurity and cripples your self-confidence.

That’s why coming across my diaries when I was going through several of my boxes in storage was way better than an expensive session with a therapist. Because when you’ve written about your life almost every week for more than 20 years, your inky words become an intermingled story of love, death, fun, hope, despair and joy.

Writing my diary with a view to it never being shared means that every emotion is candid. The late-night diary entries after I’ve come back from the Artful Dodger and the Zoo and the Cage - pubs and clubs that have long-since closed in Bournemouth - are particularly insightful.

Equally important is that over the years, I’ve written a lot about my family – my brothers, my parents, Matt’s wedding in Canada, my grandparents and my nieces and nephew.

And seeing my anger and bewilderment over my brother’s death in lists of words (I wasn’t capable of writing long sentences) is painful yet, at the same time, powerful.

Reading through the more-recent diary entries in 2010, 2011 and 2012 makes me realise that I’ve come out the other side and that up days and down days are completely normal.

Because as much as I’ve moved on there are still days that blindside me and bring to a stop.

Realising that I’m about to turn 36 is one of them.

Matt hanged himself two months after his 35th birthday. Last year, I caught up with him and that was strange. This year, I overtake him, meaning that my big brother has indefinitely become my little brother. And that’s hard to get my head around.

It means that I’ve been reminiscing, including the time we hunted for sand lizards on the Bourne Valley nature reserve that backed onto my grandparents’ garden, got lost in the pinewoods on holiday in Devon and, when I was round at my brother’s at Christmas 2007 and laughed so hard my abs ached for a week.

Dwelling on the past is never good. Once you’ve skipped down memory lane you have to turn around and come right back, which is why I’m now concentrating on everything I’ve got to look forward to next year, including Just Walk in May that I’m doggedly training for.

Apart from the odd excerpts that I’ve sent to friends and former colleagues, my diaries will remain private.

But, as we all know, there’s always an exception.

I may not be in contact with my nieces and nephew now but I don’t want them to lose out in the future by not knowing about their family, what their dad was like and how much they’re loved and missed.

So when the time comes, the diaries are theirs. They might throw them in the bin. They might not know what to make of them. Or they might just read them and be glad.

I’m walking 60km across the South Downs to raise £2,000 for Winston’s Wish. Please sponsor me here. Together we can make a difference to bereaved children’s lives.