Two days earlier 52-year-old Trigg had rowed with Susan over a debt of around £500 ex-boyfriend, Dan Barnaby, owed her.
Trigg was given a police caution for assault after she was left with a bloody nose and bruising to both her arms.
He told officers he threatened to leave her because of her 'excessive drinking' and she agreed to cut down.
The father-of-one told police: 'I thought it was not right he should owe her all that money, this caused an argument.
'She became very argumentative and abusive while in a state of drunkenness.'
After making up over a bottle of vodka, Trigg went out to buy more vodka the next day and came back at around 7pm.
The couple then watched TV and held hands 'saying how much we loved each other', according to Trigg.
Lewes Crown Court heard today how that night they slept on a three-seater with Susan on her back with her head in the middle of the sofa and legs over the arms of the chair.
The jury were told Trigg got up to go to the toilet at around 2am and noticed she was not moving or making a noise but he did not think there was anything wrong, he then went back to the sofa and got into the same position with her head on his chest.
He said he then got up at around 8.15am and found he was lying on top of the mother-of-two with his stomach covering her face.
Trigg told police: 'When I first got up I didn't think there was any great urgency, I just thought she was asleep. If I thought her life was in danger I would have done something.
'When I got up again I took one look at her and realised she had changed colour, I had moved from lying next to her to lying across her.
'Her face was purple, I thought 'oh my God she's dead'. She didn't wake up, I grabbed her leg and said 'stop playing games', her right hand was warm, I think because I had been lying on it but he left hand was cold. There was no sign of life.
'I thought she was pretending to be asleep and playing around, it's something she did sometimes.
'Initially I thought she had died through drinking, she drank a lot for a small person, easily a bottle of vodka a day, so I thought she could have died from heart failure or something.
'I panicked, I didn't know what to do, I went over to the newsagents to get some *advertiser censored*, I hoped that when I came back she would have been awake.
'I started holding her hand hoping she would wake up. I didn't call an ambulance because I couldn't accept she was dead. I needed someone to come to have a look to make sure I wasn't imagining it.'
Trigg then called his brother, Michael, and neighbour Hannah Cooper, who eventually called an ambulance.
The former chef met Susan in a rehab and homeless centre called St Clare's Community Hub in Worthing.
She bought the flat they then shared together in Worthing after both were living on the streets for a couple of months.
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