A woman who killed her ex-partner after drugging him and mutilating his genitals is a “gentle, kind and polite person” who was concerned about the welfare of the children they had together, a court has heard.

Jian Chen, 49, is being sentenced for the manslaughter of 48-year-old Xian Peng in her home in North Ryde in February last year.

Mr Peng was visiting his former de facto spouse after returning from China with his new girlfriend, when she gave him soup spiked with sleeping pills.

Once Mr Peng was asleep, Chen bound his hands and feet and stabbed him a number of times in the neck and groin, before cutting off his penis and scrotum.