Most aren't separatists. That is a Russian lie eagerly spread around the right wing sites and perpetuated by those who know nothing about Eastern Europe or the history of Ukraine. This map is the clearest refutation of that Russian lie. In 1991, Ukraine held a referendum with regard to independence. 86% of the population voted and even the Dombas and Crimea supported independence from Russia - 92% overall voted for independence.You forgot the part about California, Arizona and Texas are separatists and you as the USA have been bombing your own countrymen for a couple years ahead of time.
With Putin coming to power, that tiny pro Russian minority in the Donbas and larger one in Crimea were exploited to generate an insurgency to try and destabilize Ukraine. Russia then used that destabilization to send in troops to "protect" the oppressed pro-Russian population in the Dombas, and invaded Crimea. You'll note this is a similar pattern Russia and China used with Marxist revolutionaries throughout the Cold War.
The only aggressor from day one of Ukrainian independence has been Vladimir Putin and the Russian state.