Scollay, a cleaner, accepted her actions had fatal consequences but denied murdering her husband at the pair's Edgeware Rd home in February last year.
There were only two possible verdicts - guilty of murder or guilty of manslaughter, defence counsel Rupert Glover earlier told the court.
Mr Scollay's father Christopher witnessed his son's spiral into depression, and even offered to pay for counselling, which he had taken up.
Meanwhile, his dramatic withdrawal from society, and refusal to attend family functions, was sending his wife into her own deep despair.
Her son Louis, now aged 20, told the court she often didn't get out of bed until 3pm. She struggled to hold down a job.
One of her eight siblings, Angela Wilson told the court the family encouraged 'Lulu' to leave her beloved 'Guido' and "get her life back on track".
"Though we knew the relationship was very dysfunctional I never expected her to do something like this."
In December 2012, when Scollay bumped into Greg Van Dyk, an old flame who she had an affair with 13 years earlier, she realised her life had only got worse over the intervening years.
On the night of February 9, last year, she and Mr Van Dyk had enjoyed an evening out drinking.
As he dropped her off at her home, she became upset and emotional, saying she "felt she wasted her whole life" and that her husband - who she still loved - wasn't getting any better.
While walking up her long driveway, Scollay decided to kill her husband, the Crown says.
She took a large kitchen knife into the bedroom where her husband of 20 years was sleeping.
Rolling the 48-year-old onto his back, she straddled him as he was still half-asleep, brought the knife up and plunged it into his chest - a single wound that penetrated his heart.
But she never meant to kill him that night, says her defence.
Watching her "obviously quite brilliant husband" deteriorate over two decades resulted in "pressure building up ... to a point where she simply broke", defence counsel Rupert Glover says.
She only wanted to somehow shake him out of his funk and make him realise just how "desperate" their lives had become.
"There is no way she doesn't take responsibility for her actions... but that's not the same as having murderous intent," Mr Glover said.
"What is on trial here is the state of mind of this woman - nothing else."
There was no evidence to suggest Scollay was "a premeditated murderer", he said.
In her closing address, Crown prosecutor Catherine Butchard said the key issue for the jury is whether the Crown has proved that Scollay had a murderous intent.
Despite her immediate remorse and regret, and desperate attempts to stem the massive blood loss, the jury needs to decide that whether, in the moment, she meant to kill him, either deliberately or recklessly.
If they do not believe she had murderous intent, she will be found guilty of manslaughter.
Justice Cameron Mander will sum up at 10am tomorrow before the jury of seven women and five men begin their deliberations.
