Mr King told the Herald earlier today he didn't expect such a huge reaction to the post.
He said he had to post about his experience and would feel a hypocrite if he didn't, given that he spoke to schools, community groups and corporate organisations about living and dealing with depression.
"For too long in this world we tell kids what to do but we don't actually do it ourselves, so in the last few years me and the Key to Life Trust have taken the view 'don't tell me show me'. It seems to have resonated, especially with younger people. Most young people in this world have never met a flawed adult in their life, every adult in their life is absolutely perfect and then they come across a flawed adult and they see life through different eyes."
Mental illness was still on the rise not only in New Zealand but all over the world as people still struggled to talk about it, he said.
He wanted younger people, especially, to know that nobody was perfect and it was okay to have problems.
"And that can you have depression and still go on and have a successful career and be a successful person and parent."
He said he got the biggest shock once he realised that he'd been in a black hole over the summer months, and even now he was still fighting through it.
He thought he would have learnt after going off his medication about three years ago.
"And then to be bitten in the arse again was a shock. And the biggest shock was that I didn't expect it."
Speaking about his latest battle was almost therapeutic, he said.
"It's healing for me because there's a lot of people out there wondering about my behaviour and the thing is when you are depressed and become negative and don't return phone calls and become really short with people, that all needs an explanation."
He also admitted making nasty comments on social media, so the best way was to post on social media.
"I couldn't get to all those people myself, so that was the quickest way," he said.
In the post, he wrote how he threw himself into his work and if he wasn't working he was painting, "anything to keep myself busy, anything to stop that annoying voice in my head telling me I was useless."
But he managed to pull himself out of it while working on a TV project in Dunedin with good friend Dale Husband, who he described as one of those "beautiful souls who 'sees the good in everything and everyone and likes nothing more than brightening people's days with a kind word".
"We were standing in the Octagon getting ready for another full on day of filming when Dale started charming a group of locals and making them laugh. The first thought that popped in my head when I heard them was 'oh for f*** sake will you shut up! No one can be that happy all the time, surely?'
"And that's when the penny dropped. Within a millisecond of that thought popping in my head I said out loud to myself 'you've got a problem and you need to get it sorted!'."
He wrote how at first he thought he was just having a few bad days which would pass, but as the days turned into weeks, and the weeks turned into months things got worse.
"But here's the thing, instead of recognising I had a problem, I thought everybody else was the problem. That's the nature of depression. When you're in it, it overwhelms you. Little by little it takes over, it dominates and then finally it suffocates you. I became highly sensitive and very negative. Other people's looks and comments would be misinterpreted which led to frustration and anger, followed by regret, remorse and inevitably back to anger. To cope I threw myself into my mahi [work], and when I wasn't working I was painting."
He felt as though a weight had been lifted off his shoulders, but was then struck by emotion and guilt "at what a nightmare I must have put my loved ones through while fighting my demons".
He recalled seeing the apprehension in partner Jo Methven's eyes when he walked in the motel door that night and relief when he said he'd make an appointment with the doctor.
"That's when she hugged me and said 'that's a really good idea babe' but I knew in her head she was saying 'thank f*** for that' and rightly so," he wrote.
Mr King's manager David Steele said he was aware of his client's latest battle but was in awe of how he was able to deal with it.
"He's always fighting it but he's doing an amazing job. I had a catch-up with him yesterday and he's pretty upfront about it but it's unbelievable how well he deals with it, it's quite amazing."
However, he said it wasn't easy for him and the depression "comes and goes".
"It's hard ... he's turned his life around and basically spending all his time helping others now and I think that's probably how he copes with it, by just working with youth, working with schools and working with youth suicide or prevention of that."
A key way Mr King did that was through the charitable trust, Key to Life, a community peer support group aiming to change the way New Zealanders think, act and feel about mental health and suicide.
Read his full confession here:
Where to get help
The Mental Health Foundation's free resource and information service (09 623 4812) will refer callers to some of the helplines below:
Lifeline -- 0800 543 354
Depression Helpline (8am to midnight) -- 0800 111 757
Healthline -- 0800 611 116
Samaritans -- 0800 726 666 (for callers from the Lower North Island, Christchurch and West Coast) or 0800 211 211/(04) 473 9739 (for callers from all other regions)
Suicide Crisis Helpline (aimed at those in distress, or those who are concerned about the wellbeing of someone else) -- 0508 828 865
Youthline -- 0800 376 633, free text 234 or email talk@youthline.co.nz
