She was sentenced on the basis that her mental illness emerged suddenly and without any warning, and she had no memory of committing the offence.
Chilvers, 33, from Northwich, Cheshire, denied any wrongdoing and subsequently went on trial at Manchester Crown Court, where he was convicted last month of controlling or coercive behaviour.
Reporting restrictions were lifted on the case on Thursday as Chilvers was jailed for 18 months.
The court heard that Lesicka killed James after suffering a mental breakdown triggered by Chilvers's bullying.
The pilot had repeatedly threatened to kill Lesicka if she removed their son from his care and demanded they continue to live together at a new home he bought in the Cheshire village of Wincham.
Chilvers warned her in a "visceral" phone call played to the jury that she did not have the financial resources to win a custody battle and screamed at her: "I want James to have brothers and sisters... not a half brother and sister with a ----ing moron that you find."
The 33-minute phone call made on the morning of August 26, before the killing, included Chilvers screaming profanities at her.
The pilot, originally from Stoke-on-Trent, had downloaded an app on to his mobile phone which enabled him to record his calls.
Rob Hall, prosecuting, said Chilvers's intention may have been to aid any forthcoming legal proceedings over his son's future, but instead he had inadvertently confirmed his "bullying, controlling, self-centred nature".
Police were called to Lesicka's Wythenshawe home in the early hours of the next morning to a report of a domestic incident. They discovered the body of one-year-old James in the bath. He had suffered "catastrophic" stab wounds.
Lesicka had left before police arrived and travelled to hospital with Chilvers for treatment for serious, self-inflicted stab wounds.
Detective Chief Inspector Richard Eales, of Greater Manchester Police's Major Incident Team, said: "This has been one of the most devastating and complex cases that I have ever come across. The death of James sent shockwaves through the community.
"Peter Chilvers inflicted significant domestic abuse towards Magdalena Lesicka over a sustained period of time, which the court accepts contributed towards a break down in her mental health on that fateful evening in August 2017.
"If people take anything away from this heartbreaking case, please let it be that there is support and help available for those who are suffering at the hands of domestic abuse."
The couple had been in a relationship since 2010, although Chilvers cheated on Lesicka from 2014 with another Ryanair cabin crew member.
In the days before Lesicka killed her son on August 26, 2017, she searched the internet on "Taser UK law", "self defence weapons UK" and "killing in self defence", before later contacting the domestic abuse charity Women's Aid.
She also phoned Greater Manchester Police and two police officers were sent to her address in Beaford Road on August 25, where she showed them bruises to her arms and thigh.
Lesicka was told the next day that Chilvers would be arrested after he flew back to the UK but, terrified of the repercussions, Lesicka told officers she did not want that to happen.
She was however told it was police policy to take positive action over such allegations.
The Crown accepted Lesicka's defence that she killed James following a breakdown induced by the "deliberate, relentless and ultimately overwhelming psychological torment" inflicted by Chilvers who had portrayed a "landscape of unending misery if she did not comply with his demands".
The court heard that Chilvers's "controlling or coercive behaviour" between December 2015 and August 2017 included using or threatening physical violence, forcing her into degrading sexual acts, isolating her from her friends and restricting her finances.
Chilvers also nicknamed Lesicka "sheep" and referred to himself as a "sheep owner". She told the jury the pilot would pick loose hairs from his forehead and force her to swallow them.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• LIFELINE: 0800 543 354 or 09 5222 999 within Auckland (available 24/7)
• SUICIDE CRISIS HELPLINE: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• YOUTHLINE: 0800 376 633 ,free text 234 or email talk@youthline.co.nz or online chat.
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757
• SAMARITANS – 0800 726 666.
