There was loud applause and a shout of "rot in hell" in court as Celaire, a convicted rapist with a history of violence against women, was jailed.
"You present a very real and continuing danger to young women with whom you enter into a close relationship," said Judge Paul Worsley told Celaire, of Sydenham, south east London.
"Celaire has demonstrated time and again that he is a man with a short fuse and a propensity for violence against women," said Brian McClusky, who led Waltham Forest Borough's investigation into the attack on Kara.
"It is tragic that he has ruined the life of Cassandra's family and left Kara with severe injuries that will have an impact on the rest of her life," he said.
"Kara has shown remarkable strength and determination to be able and willing to give evidence against Celaire," he added.
(Reporting by Stefano Ambrogi; Editing by Michael Holden)