The girl was a virgin before the rape and had now changed from being outgoing to insular and afraid.
"I have lost my brother and my father still hasn't spoken to me. I hope he [the offender] is put away in prison for a long time," the girl said.
Crown prosecutor Catherine Gisler said it was a "mitigating factor" that this type of behaviour was inter-generational in the family. Ms Gisler suggested a starting point for imprisonment of six-and-a-half years.
She said the offending had resulted in significant effects on the young girl and had occurred while the girl and her younger sister were alone in their home. The offending was also premeditated, she said.
Defence lawyer David James said inter-generational abuse, an issue in the case, had yet to be addressed and this case might be the start of that.
"[The victim] had the impressions that the adults around her were complicit by knowing about this, but doing nothing about it. She carried that for six months," Mr James said.
He said the perpetrator was now genuinely remorseful.
The offending happened during a family celebration. The girl and her younger sister left the family gathering to return to their nearby home. The cousin followed them and sexually violated then raped the girl in her bed - despite her telling him to stop - while her younger sister slept nearby in the same bedroom.
Judge Phil Gittos said the man, who cannot be named to protect the identity of his victim, now fully acknowledged his guilt and the family could be left in no doubt the girl was indeed the victim.
"The effects on this young girl have been really quite devastating. The sort of things she says in her victim impact statement are all too common after horrific offending of this type," Judge Gittos said.
One of those consequences was that her family seemed to be split in two, with half supporting the girl and the other the man, which meant she did not have the support from people she could have expected it from.
The judge hoped the man's acceptance of responsibility now would help the family heal its rift.
After giving the man discounts for mitigating features, Judge Gittos jailed him for six years.