Why is The Czech Republic much closer to EU than to its Eastern Dominating Slavonic Brothers?

Slavic nations disbursed from original land more than 1400 years ago, and went on their own, distinct development without any further full-scale interaction. Slavic language are also not mutually understandable, I cannot understand Russian or Bulgarian. Historically, Czech nation was an integral part of the Holy Roman Empire and shared its fate, culture, and destiny with it, and Prague was twice the capital of this entity. Due Protestant reformation which started in Bohemia in 1419, Poles sided with Catholics and participated in crusades to suppress it, creating cultural and language split between these two nations. For example Poles refused to accept written form that accompanied Czech reformation which is hacek (áčěřšž). For next 200 years, Czech was only totally Slavic and Protestant nation in Europe and never accepted catholic faith again as its own. Existence of Russia or Eastern Slavs was unknown to majority of the population well into early 19th century, when Russian troops fought at the Austerlitz (present day outskirt of Brno). It was than to the surprise of many people to discover that there is some large Slavic nation far in the east. This naivety and lack of understanding of the Russia created Pan-Slavic movement among Czech and Slovak intellectuals, but they never were dominant force in the society. Pan-Slavic movement was chauvinistic and also it was anti-polish, where panslavic congress in Prague in 1848 kicked Polish delegation out with words that there is no places for them in Europe. This was confirmed panslavic congress in Moscow in 1867 Poles had never supported any Slavic movement and became country oriented against Czechs and Russians onward. Even in 1938, Poland supported German takeover of Czechoslovakia and Slovakian and Polish army clashed in 1939 and 1944 and again war between Czechoslovakia and Poland almost happened in 1945 for Klodzko. Experience of communism and Soviet/Russian invasion into Prague at 1968 created hatred and rejection in Czech and Slovak population anything that is ociated with Slavic and Russia. Majority of population in Poland, Czech and Slovakia still see Russia as the biggest threat to its prosperity, freedom, and stability. This drives these countries to cooperate with the West. Panslavism never make sense, since cultural, economical, social development and geography made impossible. Relationship among Slavic nations ranged from indifference to dislike to admiration to hatred (as with Serbo-Croat antagonism) as result of the Panslavism. Czechs have learned it lesson that it cannot depend on any sympathy or help or cooperation from fellow Slavs and probably the same feeling is universal for all Slavic nations. The only option is to continue developing country economically, politically, and socially to catch up with the countries of the West within EU framework.