Revolutions and civil wars are a messy business, meh. The mess in Donbass would have been less messy if they had simply been overrun without Putin's military aid
There wasn't any mess in Dobass without Russia. Only Russia started it, heated it, and wanted to show it as a 'civil war' so it could almost legally 'protect' Donbas with it's 'peacemaker forces', as it had done it in Transnistria or Abkhasia, etc. Russian FSB officer Igor Girkin (Strelkov) (now former officer) with its russian squad entered the Donbas from occupied Crimea and started combat operations with Ukrainian police, and after with Ukrainian anti-terrorist forces.
After installing a russian puppet administration in Lugansk and Donetst (major Donbass cities) Girkin resigned.
Later after that (I don't remember the exact year - 2017, 2018?) Girkin (Strelkov) even honestly admitted in an interview on youtube that it was he who lit this fire and started a real mess in Donbas.
About Girkin on WikipediaHere are his exact words (November, 2014):
"All the same, I pulled the trigger of the war. If our detachment had not crossed the border, as a result, everything would have ended, as in Kharkiv, as in Odesa. There would have been several dozen people killed, burned, arrested. And that would have been the end. And practically the flywheel of the war, which is still ongoing, launched our squad. We mixed all the cards on the table. That's it! And from the very beginning we began to fight seriously: to destroy subversive groups of right-wingers," Girkin said.
He added that he is also responsible for the further development of the military conflict, including after leaving Donbas.
"I am personally responsible for what is happening there. I am responsible for the fact that Donetsk is still being shelled. I am also responsible for the fact that Sloviansk is abandoned. And for the fact that it has not been released, I am also responsible bear responsibility," Girkin said.
He also
admitted that the decisive role in the counteroffensive of the separatists in August 2014
was played by military personnel who came from Russia.