Russia is neither fascist nor "the aggressor." Anyone who doesn't recognize that Russia entered a civil war where one side (a coup government with an actual fascist military that openly admits their fascism) was trying to ethnically cleanse the other side (who are speakers of the Russian language) doesn't know what the fuck is going on and has almost certainly swallowed gallons of propaganda.

could stop it at any minute by returning to their own territory

And then what would happen to the people of Eastern Ukraine, the Donbas? They would get ethnically cleansed. But I guess you don't give a shit about that? Or you literally didn't know about that?

and admitting that they're simply the bad guys in this war?

Baby-brained simplistic bullshit. No, Russia is not "the bad guy" in this war and you need to expose yourself to more of the world than fucking marvel movies. Also, the word fascist has a meaning, it's not a synonym for "bad guys," and if you had any exposure to the world beyond your little bubble from which you lap up propaganda like it's ice cream, you'd know that (for example) the US just as if not closer to being fascist than Russia.