Trevor Gibbon, 48, allegedly armed himself with two knives and fatally stabbed Alison Morrison, 45, in Harrow, north London, in December 2014.
The Old Bailey heard the killing came a day after he was handed a restraining order, having pleaded guilty to harassing Mrs Morrison.
He denies murder.
The prosecution said the dispute between the neighbours started when Ms Morrison, her husband Cedric and their son moved next door to Mr Gibbon and his partner, Maria Perrett, in Windsor Crescent, Harrow, in 2011.
Mrs Morrison was stabbed a day after the dispute was supposedly resolved in court, the jury previously heard.
During the hearing, Mr Gibbon told the court he had stashed two knives in a Tesco bag in his car because he was contemplating suicide following the "tit-for-tat" dispute.
But when he saw Mrs Morrison walking towards the railway station he "just went hazy".
He said: "I remember just getting out the car and walking that way.....I don't know what I was doing. I don't know what I was thinking."
Jurors heard Mr Gibbon was arrested 100 miles away and had dried blood on his hands.
The trial continues.
A man accused of stabbing his neighbour 33 times after a "tit-for-tat" dispute has said his mind went "hazy" at the time of the attack.