You are making false statements. There was no coup in Ukraine since nobody seized power illegally. After the then president resigned as a result of mass protests all over the country, there were new presidential and parliamentary elections in which new president and parliament were legally elected with no nazi party present in the parliament or government. Looks like you just repeat Putin's nonsensical propaganda. There was never civil war in Ukraine, instead it was a disguised Russian invasion initiated by the disguised Russian military who of course also managed to recruit a few local sympathizers into their newly formed military groups which would not qualify to be the representation of the significant portion of the local population anyways since those groups were organized, financed and commanded by Russia. So you are making fake Russian propaganda statements:
1) there was no coup, instead it was a mass protest with the resulting re-election of government (rather common thing in democratic countries btw).
2) there was no civil war but Russian invasion instead which actually started in 2014 but it was just disguised and non full scale with the view of imitating a civil war. So Ukrainian army just responded to the Russian aggression in the Eastern Ukraine. Btw, the occupation of Crimea was not even disguised, Russians overtly invaded it in 2014 which was already just an evident serious international crime.
Regardless of the case, you should be aware that whatever happens inside any country (coups, civil wars, etc), no other country has the right to invade it unless this country poses a threat to international security.