'I have no regrets': NSW Deputy Premier returns after mental health leave

New South Wales Deputy Premier John Barilaro said he "hit rock bottom" before returning to Parliament today, after taking time off to care for his mental health.

Mr Barilario took leave after a tumultuous few days in September when the minister threatened to split the Coalition over the government's koala protection policy.

Mr Barilaro said he was close to quitting his position before taking some time off, describing last month's drama as "the straw that broke the camels back".

"I was done, I was exhausted, I was emotionally and mentally challenged and broken, in a way," he said.

"I realised I've been running on empty for three or four months and I needed that time off otherwise I was going to probably end up exiting this game."

READ MORE: John Barilaro backs down over koala policy

Mr Barilaro said despite reflecting on his action, he has "no regrets" about the koala policy.

"I look back at some of the things I've done and it wasn't perfect it wasn't right but I have no regrets."

"The policy was right, what we were fighting for was right. We got the win but it got ugly and maybe that's something I've got to work on, but the policy was always right."

"I was always prepared to get a bloody nose fighting for the regions."

While on leave, Mr Barilaro's party came under the spotlight again with revelations of Gladys Brejiklian's secret relationship with disgraced former minister Daryl Maguire.

Mr Barilaro said he was not aware of the relationship despite "knowing Gladys better than most".

"I get to see a personal side of Gladys and didn't see any of this coming, it was something that was kept private and that's alright, she's a very private individual."

"No one knew.

"Whatever has occurred it's not for me to make judgement, I'm backing her 100 per cent."