The apartment was owned by her ex-partner's grandmother and the fire caused at least $25,000 damage.
Defence counsel Tony Balme said the case was a "rather dismal situation". He described his client as tragic and unfortunate.
"Her lifestyle is essentially quite transient," Mr Balme said.
"She has had difficulties holding down standard accommodation."
Mr Balme said imprisonment was probably the most suitable penalty, at which Kryszkiewicz whimpered. Judge Robert Wolff said the crime was premeditated and, by her own admission, Kryszkiewicz was "getting back" at the man.
"There is inherent danger in all arson cases. The victim has suffered losses that are, for practical purposes, irrecoverable," Judge Wolff said.
"You seem to have no remorse at all at the consequences of what you have done."
Judge Wolff sentenced Kryszkiewicz to three years' jail.
Kryszkiewicz wept as she was convicted and called out "I love you mum" to her mother.
In the public gallery, Kryszkiewicz's mother was comforted by the defendant's brother. Afterward the mother, who would not be named, said she hoped the judge would have taken into account her daughter's mental health.
"I'd rather see her in a mental health facility.
"We've been trying to get her help for a long time but until that person asks for help ... sometimes you can't get the help you need until you get to the bottom."