The now 40-year-old said he starting using the drug when he was about 17 or 18. Then, in his early 20s, he "got deep into it".
"I started loving it more than loving anyone else."
Witehira said at the peak of his addiction, he was using 2 grams a day.
He remembers his lowest point. "I had my 9mm gun sitting on my lap and I didn't know whether to use it on a shopkeeper or myself. That was the moment I told myself I needed a change."
Witehira said he reached out to his sister, who is involved in the Te Ara Oranga programme, earlier this year when he was living in Auckland.
"I was in a bad place. I needed change, simple as that. You start to realise it's done nothing for you. You haven't moved forward or even sideways."
Witehira said his family had told him he was not allowed back until he was off P.
After reaching out, his family picked him up, brought him back to Kaikohe and referred him to the Te Ara Oranga meth pilot programme.
He said his family had been his biggest supporters, along with Te Ara Oranga.
Witehira said it has been good to spend time with his family and friends, particularly his nieces and nephews. He said his family have kept him sane.
As part of Te Ara Oranga, Witihera has been attending a range of programmes where he has been learning about addiction, coping mechanisms and triggers.
"How to dodge them, how to cope, how to reach out to people without being whakamā (shy), they teach you those."
He said he has also been doing activities to get know himself, and learn more about his Māori side.
Witehira said he had been keeping his mind busy and has been surrounded by positive people. He has started working out in a gym he has set up in his garage.
Te Ara Oranga staff keep in regular contact with him, make sure his state of mind is good and he is keeping on track.
"They've treated us as normal people, not addicts."
He said he has been clean since he walked into the programme five months ago.
"In the first few month I nearly gave in. Now I feel I'm at a good stage."
He admits it is still early days, but he wants to get back into work at some point.
Witehira is also looking forward to having a full Christmas with his family for the first time in a decade.