The woman, aged 51, drugged and attacked her ex-husband on Saturday evening, according to Midi-Libre, which said that the couple were divorced but continued to live together in an "unstable relationship". The man remained in a coma on Wednesday.
She is reported to have first drugged him with insulin and Xanax, and then used an aerosol spray to burn the man's genitals.
When police found the couple in their home, in the Lemasson district of the southern French city, the man was immediately transported to hospital. His ex-wife was arrested, and police have opened an inquiry into attempted murder and acts of torture.
During questioning, the woman told police that she had suffered domestic violence at the hands of her ex-husband for years and spoke of a "deep hatred" towards him and a desire to "hurt" him, according to France Bleu.
Though she had never formally complained to police, she had reported her injuries to doctors on numerous occasions.
Investigators said the woman was "coherent", but will undergo a psychiatric examination.
If the suspect's report of domestic violence is proved to be true, the case could renew the argument in France for an expanded definition of self-defence in cases involving victims of domestic violence.
Jacqueline Sauvage, a woman who was jailed for ten years after killing her abusive husband, has become a symbol of this debate. More than 400,000 people signed a petition demanding her release and Hollande granted her an official pardon in February, however earlier this week a court refused to release her.