This is one of those horrific, long-term, multi-generational conflicts that have no "good" side. Right now, Russia invading the whole place rather than just making the Russian-speaking/traditionally Russian areas officially part of Russia again (or satraps) makes them the aggressor.
However, when people say "NAZI's IN Ukraine" those who are aware of things, know that isn't hyperbole, it is completely real. Some of the guys in the ultra-nationalist militias that support the current government (and some previous ones) took their Grandfather's old NAZI Ukrainian SS division Uniforms out of the closet and were wearing them. They also used SS symbology for some of their units.
Their grandfathers joined the SS originally because, in the 1930s, Russia had starved millions (and I do mean millions) of Ukrainians to death - that's that "Holdamore" thing people keep mentioning as well as forcibly relocating a lot of the population many of whom never made it home.
On the other hand, I saw chilling films of the current government (when it was new) allowing some of the "militias" to enter the Russian areas of what was supposed to be their own "nation" and terrorizing kindergartners and their parents (someone had their phone on record). A goon in camo walks up to a little girl whose five years old and says "Ah, her name is Misha, that's a Russian name" then he pinches her cheek hard and looks at Mom, "She has a Russian name, she should not have such a name she is in Ukraine, change her name or go to Russia."
The report cut off as the child looks too terrified to even cry and the mother (and other parents) are in shock - it is the custom in Eastern Europe, especially the Slavic countries for parents to go with their kids on the first day of school. Those goons knew exactly what they were doing.
Both sides are reported to have committed atrocities, both sides have killed civilians at different times and while historically there has been "A" Ukraine for quite some time, the modern boundaries are pretty modern.
So the answer is (to me) is there is no "right" side, this is a big shifting mess. On the other hand, Putin/Russia moving in to take over the entire place and also attacking Moldova does make them the aggressor in this current round of tit for tat.
It also remains to be seen if they will "settle" for Ukraine, either making part of "Russia" again or just installing a puppet government and making it a member of the "Federation," of the new Russian Empire. Or if they will continue on towards other countries and if they attack NATO, it all goes way out of control and yep, Russia sadly becomes the enemy.
Something I hoped never to see in my lifetime.
