Jordan Martin turned up at the victim's home uninvited on the morning of October 31, 2020, and subjected her to shocking violence.
The woman said the assault made her leave her home and cut contact with friends and family in a bid to ensure the 27-year-old could not track her down.
Newcastle Crown Court heard Martin had walked into his ex's home, in South Tyneside, through an unlocked door and refused to leave when she told him to.
Prosecutor Caroline McGurk told the court: "The defendant attacked her from behind, pulling her hair and grabbing her right hand as he bit the top of her head."
The court heard how the victim was repeatedly punched to the head during the assault, which happened in front of children and left her bruised.
Martin refused to leave the house for four days after the attack and demanded money so he could buy drugs.
The victim said in a statement read to the court: "I feel scared of Jordan.
"This was out of character.
"I have had to leave our family home and ask the police to keep us safe. I knew I couldn't go to friends or family members because he would know where we were and find us.
"I knew if I gave him money for drugs he would be calm enough to let us leave the house.
"I have had to stop contact with friends and family through fear of Jordan finding out where I am."
Martin, of no fixed address, denied assault but was found guilty after a magistrates' court trial.
Mr Recorder Christopher Williams sentenced Martin to nine months behind bars with a three year restraining order.
The judge said: "It was an attack on her in her own home."
Penny Hall, defending, said Martin had "a big problem then" with drugs and does now accept wrongdoing "to some extent".
Miss Hall added: "He has accepted fully the relationship is over.
"He is now drug free and hopes to stay that way."