"Most of my family are in even worse condition than I am," he said in his victim impact statement.
He said his grandmother every day replayed voice messages Jennifer had sent her.
The son said Li had smirked during the murder trial.
"I couldn't see a single hint of remorse. His words sounded like he rehearsed them."
He said his mother's final moments would have been terrifying.
"She looked at this world one last time and took her final breath ... My mother's life ended with fear, sadness, worry and pain."
At his trial, Li accepted he must have stabbed Yang but insisted he was not in his right mind.
Li, 65, also denied breaching a protection order.
He frequently tried dodging questions during cross-examination, replying with queries of his own or telling Crown prosecutor Nick Webby stories about mythical creatures.
He identified multiple aggravating factors, including Yang's vulnerability, the calculated nature of the attack, and its intense brutality.
Li was sentenced to life in jail with no chance of parole for 19 years.
Outside court, Detective Sergeant Ryan Bunting of Waitematā CIB said the murder was a sensless act which shocked the community and witnesses.
He thanked members of the public who tried stopping Li from getting away and people who tried performing first aid on Yang.
"She was a much-loved mother, sister and daughter who was simply trying to live her life."
1997: Yang and Li are married in China. 2001: Yang and Li migrate to New Zealand and buy a house in Blockhouse Bay. 2005: The couple separate in August. Yang moves to Avondale. In December, a protection order for Yang is granted. 2007: Li is convicted for breaching a protection order. 2009: Yang and Li are finally divorced. 2014: Li is again convicted for breaching a protection order. 2016: The High Court dismisses an appeal Li lodged about division of property, and a judge finds Li was dishonest in much of his evidence.
Days before murder: June 23: A letter is sent around this time to Yang's son, warning the recipient to leave New Zealand or be "exterminated". July 18: Li buys a knife at Mitre 10 Westgate. July 22: Li buys a tactical folding knife on eBay, asking it be delivered to his Matisse Dr address in West Harbour. July 28: Li enters Hunting & Fishing, Constellation Dr. He haggles before buying a hunting knife, and shows interest in buying a machete.
July 29, 2019: 7.16am: Someone using a video camera found in Li's car starts recording Yang as she leaves her Granville Dr property. 7.59am: Footage from a Pavlovich bus shows Li's car parked on Granville Dr. 8.03am: Li, or the person using the camera found in his car, stops recording Yang. 8.07am: A security camera on White Heron Dr, Massey, shows Yang walking past. 8.20am: Witness Casey Armstrong notices a silver Honda Airwave station wagon driving slowly near her on Westgate Dr. Armstrong is spooked and takes a photo of the car. 8.30am: Pavlovich bus footage shows Yang waiting at a bus stop. 8.33am: Yang is approached and stabbed multiple times beside Westgate Dr. 8.34am: Witness Daniel Harvey follows Li on foot, but Li enters his Honda before Harvey can grab him. 8.38am: Witness Peter Simpson calls 111 and says he has used his ute to stop the silver Honda. 8.40am: The police Eagle helicopter sees Li around some nearby bushes. He's arrested without incident.
Domestic violence - do you need help?
If you're in danger now:
• Phone the police on 111 or ask neighbours of friends to ring for you. • Run outside and head for where there are other people. • Scream for help so that your neighbours can hear you. • Take the children with you. • Don't stop to get anything else. • If you are being abused, remember it's not your fault. Violence is never okay
Where to go for help or more information:
• Shine, free national helpline 9am- 11pm every day - 0508 744 633 www.2shine.org.nz • Women's Refuge: Free national crisis line operates 24/7 - 0800 refuge or 0800 733 843 www.womensrefuge.org.nz • Shakti: Providing specialist cultural services for African, Asian and middle eastern women and their children. Crisis line 24/7 0800 742 584 • It's Not Ok: Information line 0800 456 450 www.areyouok.org.nz