On Wednesday night, millions saw not only a political party but also a family ripping itself apart live on prime-time television. Mr Le Pen, president of the National Front, began by accusing Bruno Megret, the second power in his party for the past decade, of committing "crimes against France". Was the most powerful ultra-right and xenophobic force in western Europe falling apart?
Mr Le Pen went on to repudiate his own daughter, Marie-Caroline, 37. She, he said, had sided with her lover, Philippe Olivier, one of Mr Megret's lieutenants, against her old dad. Mr Le Pen, 70, putting on a sorrowful voice ("a head so old and white as this") explained: "There is a kind of natural law which carries daughters towards their husbands or lovers and away from their fathers." If this was a tragedy, Le Monde said, it was "coarse and shameless", inflicted on unsuspecting viewers.
Like King Lear, Le Pen has three daughters. Marie-Caroline, unlike Cordelia, is the eldest, and is regarded as the brightest and most politically shrewd of the three. Superficially close, they have been bitter rivals for Papa's affection and the largest share of the political and financial loot from the family business.
On Thursday, the day after her father accused her of being a silly, love- struck female, Marie-Caroline effectively resigned from the family. She accused her father of "invading my private life", subtly turned the knife in his political wound and then took a passing stab at one of her sisters.
Marie-Caroline - "Carole" to her father - confirmed that she had backed the calling of an emergency conference of NF members next month to resolve the Le Pen-Megret battle. Her father was vehemently opposed, knowing that he might lose.
Marie-Caroline explained that she had acted "neither as a daughter nor as a lover" but as "a free, woman politician, who was elected, and not nominated, to the central committee [of the NF]". The remark contains a piece of sisterly cattiness: when the NF central committee was elected last year, Mr Megret's supporters took the top positions, pushing out several Le Pen candidates; Marie-Caroline was elected in her own right but her youngest sister, Marine, 29, was not. Papa fixed it later by nominating her to a committee seat.
The middle sister, Yann, 34, is the least active politically. She is married to Samuel Marechal, head of the NF youth movement, who is one of Mr Megret's most virulent enemies, and likely to emerge as the new second force in the Le Pen wing of the French far right.
Bitchiness apart, Marie-Caroline's statement amounted to a declaration that, in her political judgment, Papa was finished. She was backing the winning side. ("How sharper than a serpent's tooth it is/To have a thankless child.")
All the sharper because Le Pen's daughters have been daddy's girls, emotionally and politically. When he broke up with their mother, Pierrette, in 1987, the sisters sided with him and savaged her (especially after she took graphic revenge on her husband by appearing as a Playboy centrefold).
Pierrette, still estranged from her daughters, claims that her former husband indoctrinated them from childhood with his paranoiac world-view. This can be encapsulated as follows: France is threatened by an international conspiracy of Jews and Freemasons. Through a devilish cocktail of European federalisation, immigration and American cultural imperialism, they are determined to destroy the French race and culture.
Whatever one's view of last week's events in the NF - almost certainly the end of the French far right as a unified force - one should not cast Marie-Caroline Le Pen and Bruno Megret as moderates. Modernisers yes; moderates never. Mr Megret's views, in private, are said to be more extreme, more ideologically racist, than Mr Le Pen's. But he believes - and presumably Marie-Caroline agrees - that the movement's goals can only be achieved by escaping from the ghetto of vulgarity and provocation created by the old man.
Mr Le Pen's internal NF difficulties began when he assaulted a Socialist woman candidate before the second round of the parliamentary elections last year. He did so while campaigning with, and for, Marie-Caroline, who went on to fail (just) to win a national assembly seat in Mantes-la- Jolie, west of Paris. In the running battle that followed, between NF supporters, leftist demonstrators and the police, I was squashed up against father and daughter for several minutes. Jean-Marie said pompously: "This is nothing to me. I was once a paratrooper in Algeria."
Marie-Caroline looked unperturbed, even bored. She just said: "Oui, Papa." With hindsight, one speculates that she was thinking: "Silly old fool. Look at all the bad publicity you're going to get us again..."
In the mood of Third World, post-coup paranoia that now reigns in the NF, Mr Le Pen accuses his eldest daughter of setting a "trap" for him in Mantes-la-Jolie. He says that she conspired with the Socialist candidate and leftist demonstrators to get Papa into trouble, as part of a plot to smooth Megret's path to power.
Le Pen has loved to pose, Lear-like, as "a man more sinned against that sinning". More appropriate, however, is a line from Act Four, Scene Six of King Lear: "Like a scurvy politician, seem/To see the things thou dost not." Or better still, Act Four, Scene Seven: "I am a very foolish, fond old man ... I fear I am not in my perfect mind."