There was no fight for an enemy nation in Odessa. There were anti-Maidan protesters.
Who wanted to secede and join Russia.
Except that it was not even proven that it was Yanukovich who used the snipers. And he wasn't indiscriminately shelling civilians in western Ukraine either. I have a coworker from Ukraine, his extended family in Donetsk (a young woman with two children) was killed by Ukrainian artillery.
That's tragic but blame the people who started the war.
What invasion are you talking about? There is a civil war going on. Irregulars on one side, quickly legalized former irregulars on the other side. Ukraine would never stand a chance against an actual invasion from Russia. Compare that to the utterly professional and practically bloodless annexion of Crimea. And this is why Ukrainian army doesn't even try to do anything about that, they know they don't stand a chance. Shelling cities, on the other hand, is easy. Especially these in Eastern Ukraine - Galicians don't consider Eastern Ukrainians to be real Ukrainians, even though they themselves were ousted from Poland when ethnic Poles were thrown out of Western Ukraine after WW2. They don't even speak the same language - a mix of Ukrainian and Polish by the Galicians, Surzhik by Eastern Ukrainian.
Russia is promoting, recruiting, and supplying the rebels. Russian soldiers are shelling across the border. It's not official Russian troops in Ukraine but it's sure as hell a Russian invasion.
Svoboda was recognized as a neo-nazi party by basically every European country. And even though this party was in minority in the last elections, they suddenly have received a lot of interesting positions after Maidan because their armed thugs helped the coup. And what followed were banning oppositional parties, censorship of media and other nice things that typically follow after a fascist coup.
Everything except the fascism of course.
An invasion has to happen first. Then one regular army can fight another regular army.
Did you miss Crimea? The floods of Russians streaming across the border being equipped by the Russian government.
And you're still dodging the question. Tens of thousands of foreign fighters stream across your border, occupy your cities, and claim them as an independent state.
What do you do?