Andrew Wood, 33, became increasingly threatening and possessive towards the victim who he had been in an online relationship with after meeting on the dating website Plenty of Fish.
When she tried to distance herself from Wood, he bombarded her with phone calls, emails and messages in which he threatened to kill himself.
In just under 18 months, he sent more than 16,000 emails to her.
He also threatened to send intimate photos that the victim had shared with him to her parents and friends, Teesside Crown Court heard.
Wood also told her he had put pictures of her son on a paedophile website, said prosecutor Saba Shan.
The court heard his actions intended to cause her “maximum distress and humiliation” and significantly affected her mental health.
In an impact statement read out in court, she stated: “Not knowing if or where my private images have been shared online causes me great distress.
"I could have strangers looking at really personal photos of me and I find this really unsettling.”
Wood, of Meadowsweet Road, Hartlepool, pleaded guilty to threatening to disclose private sexual photographs with intent to cause distress and harassment.
He also admitted breaching a sexual harm prevention order previously made by the court to monitor Wood’s behaviour after he deleted WhatsApp from his phone.
Simon Gray, mitigating, said Wood was vulnerable due to having autism and “profound lifelong mental health problems”.
But Judge Tim Stead said the offences were too serious and sentenced him to two years in prison.