A definition of hatred towards your own nation There are such things as xenophobia, nationalism, etc. In other words, various forms of hating and diminishing the foreign and the foreigners. 

My question is, is there a term meaning hatred and disparagement towards your own people or culture? Some kind of your-own-nation-phobia? 

I don't mean xenophilia, because that's affection towards foreign, it doesn't mean hatred towards your own. I mean exactly hatred towards your own people/nation/culture/etc.

EDIT1: Just one of the examples of how this phenomena may work. An international conference. A person from, say, Russia, talks to a group people from various countries. Suddenly, another Russian joins the group. Our hero realizes that (either he knew that that person was a Russian beforehand or reads that on their badge) and an anger and disgust start boiling within him. He starts to be prejudiced and a bit aggressive towards his compatriot because that person is his compatriot.
The word "Oikophobia" has several different definitions.  In psychology, it usually means an aversion to home surroundings, or to objects in the home.  However, the British philosopher Roger Scruton coined a new meaning, which is exactly what you are looking for:


  The disposition, in any conflict, to side with 'them' against 'us', and the felt need to denigrate the customs, culture and institutions that are identifiably 'ours'.
  -  Roger Scruton, quoted on Urban Dictionary


Wikipedia has a more detailed description of the term:


  Scruton uses the term as the antithesis of xenophobia. In his book, Roger Scruton: Philosopher on Dover Beach, Mark Dooley describes oikophobia as centered within the Western academic establishment on "both the common culture of the West, and the old educational curriculum that sought to transmit its humane values." This disposition has grown out of, for example, the writings of Jacques Derrida and of Michel Foucault's "assault on 'bourgeois' society result[ing] in an 'anti-culture' that took direct aim at holy and sacred things, condemning and repudiating them as oppressive and power-ridden."
  
  "Derrida is a classic oikophobe in so far as he repudiates the longing for home that the Western theological, legal, and literary traditions satisfy. . . . Derrida's deconstruction seeks to block the path to this 'core experience' of membership, preferring instead a rootless existence founded 'upon nothing.'"
  
  An extreme aversion to the sacred and the thwarting of the connection of the sacred to the culture of the West is described as the underlying motif of oikophobia; and not the substitution of Judeo-Christianity by another coherent system of belief. The paradox of the oikophobe seems to be that any opposition directed at the theological and cultural tradition of the West is to be encouraged even if it is "significantly more parochial, exclusivist, patriarchal, and ethnocentric."  Scruton described "a chronic form of oikophobia [which] has spread through the American universities, in the guise of political correctness." 
  
  Scruton's usage has been taken up by some American political commentators to refer to what they see as a rejection of traditional American culture by the liberal elite. In August 2010 James Taranto wrote a column in the Wall Street Journal entitled Oikophobia, Why the liberal elite finds Americans revolting in which he criticized supporters of the proposed Islamic center in New York as oikophobes who were defending Muslims who aimed to "exploit the 9/11 atrocity".
  -  Wikipedia