It is very sad about what happened in Odesa a year ago.
However...
it was the pro-Russian group who started it. People from the Ukrainain crowd were the first to die, but by the end of the day, the pro-Russians took the worst of it.
Btw, your chronology is off by saying that Odesa tragedy (on May 2) led to “civil war”. Russian FSB colonel Girkin advanced on Sloviansk in mid-April, and Russian specnaz taking over Ukrainian government buildings in Donetsk and Luhansk was even earlier. So it would make a nice narrative if Odesa preceded all that, but the dates don’t match.
Strelkov and other events may have predated by a few days, but it was Korsun, the Odessa Massacre, and finally the Mariupol Massacre, that convinced thousands of ethnic Russians that they had to fight, or die in the ethnic cleansing.
One HOUR of footage combined from numerous sources of that Odessa Massacre, one year ago this week.
https://www.youtube.com/watch?t=48&v=aO1A4aqgamA