Dean Yarnton recalled the night he woke up in his ute, with a gas bottle hissing in the back seat, and his wife, Sharon Yarnton, missing from the driver's seat.

"I jumped out of the car and my socks were automatically very wet and [there was a] strong smell of fuel. I looked down and saw a car taking off in another direction," Mr Yarnton told a NSW District Court jury on Tuesday.

Ms Yarnton, 50, a former prison guard, is on trial for the attempted murder of her husband at Picnic Point in the early hours of February 1, 2015, alongside accused accomplices Monique Hayes, 25, and Fady Houda, 24.

Prosecutors allege there was "animosity" between the Yarntons when Ms Yarnton discovered her husband of 23 years was having an affair, and she enlisted Ms Hayes and Mr Houda to help her kill him.

All three have pleaded not guilty.

Mr Yarnton, also a prison guard, told court he and his wife were planning to divorce in early 2015, and were living together at Menai while their house was on the market.

On the night of January 31, Ms Yarnton, convinced him to have one final dinner "as the awesome foursome" with a pair of old friends.

After drinks, dinner, and playing the pokies at Merrylands bowling club, Ms Yarnton asked if he wanted a drink.

"She insisted on buying the last beer of the night, just for a final goodbye," Mr Yarnton said.

Mr Yarnton said he noticed something unusual about the drink.

"I took a sip of the beer and it tasted really funny, it was really powdery on the tip of my lip."

He said Ms Yarnton went to the bar to get another beer, but that also tasted strange and he began to feel drowsy.

"It was a feeling I haven't had before, where I was continually yawning all the time."

Mr Yarnton said he fell asleep in the car on the way home, and then woke up in the ute.

"[I remember] waking up in a dark place with a gas bottle blaring away in me ear, and no one to be seen. Just myself in the car and this gas bottle blaring away."

After jumping out of the car, Mr Yarnton said he saw another gas bottle close to the ute's fuel flap, and noticed petrol around the car.

He saw a car driving away, and immediately called his wife.

"I said 'What the f--- is going on here?' She said 'I've shit myself, I'm in the bush cleaning myself up. I said 'Bullshit'."

Mr Yarnton said Ms Yarnton emerged from the bush, and he pushed her up against the car.

"I said 'What the f--- is going on?' She said 'You've just lost your job c---. I'm calling the police and having you charged with assault'."

The trial continues before Judge Paul Lakatos.