“She could not resort to the law,” Denis Prieur, a psychiatrist, told the court. “There is no other possibility than to make him disappear,”

By contrast, the public prosecutor, standing just a few feet from Ms. Bacot, who kept her head bowed, said on Friday that the act was premeditated and could not be excused.

But he also took into account Ms. Bacot’s enduring suffering, requesting only a five-year jail term, of which four years would be suspended, meaning she would not face further incarceration since she already had served one year in prison.

Ms. Bacot, who faced life sentence, said in her book that she expected to return to jail after the trial. Taken by surprise by the prosecutor’s request, she passed out for a few minutes, overwhelmed with emotion.

Ms. Bacot’s case strongly resembled that of Jacqueline Sauvage, who was sentenced in France to 10 years in prison in 2014 for killing her abusive husband, leading to similarly fierce debates about self-defense in cases of abuse. Ms. Sauvage was eventually granted a presidential pardon in 2016, after she had become a symbol for the fight against domestic violence.

Domestic violence has become a growing issue in France, where 146 women were killed by their current or former partner in 2019, according to government data, an increase of 21 percent from 2018. The government has introduced new measures to combat the problem, like more education and more social workers in police stations, but many activists say the efforts do not go far enough and are underfunded.

Ms. Bacot’s children told the court that they went twice to the police in the early 2010s to report their father, but that no action was taken. The police said they had found no trace of these exchanges.