Mark Titley, who was locked up for manslaughter in 2012, began demanding money for ‘clothes, food and drink,' but became aggressive when she refused to send it, in June last year.
Prosecutor Lucky Thandi said the calls became 'relentless' and, in September, Titley wrote to say other inmates had been told where she lived and they would get her.
Over two months he made 450 calls and was still contacting her in May, this year.
After the prison number was blocked, Tittley, aged 48, continued to bombard her with abusive letters using different prison numbers to avoid interception.
In a statement, she said: "I am aware he is due out on April 22. I am fearful of what he will do to me and my family.
"I am on edge daily. I don’t understand why he is getting angry with me. I don’t want him to come near me."
Nottingham Crown Court heard that Titley was jailed in 2012 and served six years of a ten-year sentence before he was released on licence in 2017.
But he was recalled to prison two months later because he failed to sign in with his probation officer.
David Watts, mitigating, said Titley maintains his denial but says he was ‘motivated by concern for his mother about what others said.’
Titley, appearing by video-link from HMP Nottingham, interrupted proceedings to say: "I am remorseful for upsetting my mum in this way. I was getting lied to in prison."
He was convicted of harassment intended to cause fear and distress after a trial on May 31.
On Tuesday, Judge Steven Coupland said the offences were done ‘out of revenge for not sending you cash,’ and his mother was ‘left terrified about what you might do when you were released.’
"You were given the opportunity to change your ways and plainly you haven't,” he said. “This type of drip-drip-drip communication is corrosive. This is your fault, not hers.”
Titley will serve three years in custody before he is eligible for parole, and a one-year extended licence. He was banned from contacting his mother and other family members.