Jessica Silva dealt with her violent drug-addled boyfriend's abuse for so long, she thought she could change him.

But on Mother's Day 2012, James Polkinghorne told her over the phone: "I'm going to cave your f---ing head in" and "I'm gonna break your f---ing jaw 'cause you're a dog."

Hours after making the threatening phone calls, he turned up to her parents' home, in Marrickville, in Sydney's inner west, high on ice and in a violent rage.

Ms Silva stabbed Mr Polkinghorne five times in the back and face outside the house.