The man, identified as Kuriakose, attacked Dayanidhi yesterday at the veranda of the first class magistrate court, police said. Kuriakose has been arrested.
The 45-year-old Sri Lankan woman, who has taken Indian citizenship, met Kuriakose in Mumbai and entered wedlock some years back.
However, they were estranged since the past three years, police said, adding that there were at least 16 cases pending against the accused in various courts.
The estranged couple had come to the court in connection with a domestic violence case filed by the woman against Kuriakose. It was there that the man lunged at her with a surgical blade, police said.
Policemen immediately came to the woman's rescue and overpowered Kuriakose. The woman suffered deep wounds on the neck. She has been admitted to a hospital here.
The functioning of the court was held up for some time following the incident.
A case under Sec 307 (attempt to murder) of IPC has been registered against the accused.