Lingman said he desperately wanted to tell somebody what happened after Chance was shot dead at Kingseat in South Auckland on February 24, 2019.
Defence counsel Ron Mansfield asked Lingman to outline events after the shooting.
Lingman said he initially left Chance's body behind a flatbed trailer and told jurors what he was thinking afterwards.
"Do I leave Denver there or not, behind the trailer?"
"So many different scenarios: What if, what if, what if? I've got pill presses in my garage... a big grow room... When should I go to the police?"
But he never went to police.
Instead, police arrested him the next month after finding Chance's body in a chest freezer on the Kingseat property.
Lingman said he planned on confessing, but was waiting for his partner to return from overseas and needed to look after his child.
He explained what he did with Chance's body.
"I picked Denver up from under his arm. I dragged him over towards the freezer and then lifted him up and I put him inside from his head first.
"His legs were stiff. I was trying and trying and trying to bend them in.
"It horrifies me every f***ing day. I guess it's out of desperation but f***, I started my chainsaw up and cut his legs. I cut Denver's legs so I could just shut that freezer door."
Lingman said he was disgusted at himself then for mistreating Chance's body, quickly went to throw up, and remains disgusted with himself.
"Even last night, I think about that. And it's the most horrific thing I've ever done in my life or will do."
He added: "I didn't want my [child] to see a dead body... I'd gone that far by putting him in the freezer but the freezer was too small."
Lingman told jurors he wanted to drink a lot and he was mixing benzodiazepines and alcohol.
"Everything just went down. My state of mind and everything. I just wanted to get out of that house. I didn't want to be there."
He spent some time moping and described one occasion when he drank vodka straight from the bottle.
"That was one of the first times I could actually think about what's happened. So that was really hard... everything was gonna change."
His voice cracked as he said he realised life for people close to him would also change because of the homicide.
He told jurors he self-medicated "because of the enormity of what just happened on the 24th".
"You've got to deal with it somehow."
There's no dispute Lingman shot Chance with a Ruger semi-automatic rifle outside the front door of the Kingseat house on February 24 that year.
But Lingman has argued he acted in self-defence.
"Who could I tell? I wanted to tell someone. After what happened, after a while it's like I put my head in the sand," he said today.
The trial continues.
