You could not be more wrong.
The first Sith (if we are referring to the Hundred Year Darkness) abused their Dark powers by twisting creatures and deforming them, turning them into monsters. The Jedi told them to stop, but they refused, leading to their exile. Then they come back with more twisted creations and wage war on the Jedi Order, which they lost badly. Then the Jedi banished the survivors to the Unknown reaches of space. The Jedi could have killed them, but banished them instead.
Flash-forward and Naga Sadow leads a massive invasion of the Republic, which is put down after his student betrays him. The Republic then decides to invade Sith space to prevent another war. Some Sith killed themselves through Dark Rituals. Some made suicide attacks on Republic forces. Many were killed by the Sith Emperor. Others were severed from The Force by Odan-Urr. The number of Sith that were actually killed by the Republic is quite low. And technically, the Republic's invasion of Sith Space was apart of the Great Hyperspace War. So the Sith are victims of their own war.
Actually the Hundred years of Darkness. Started when the jedi decided not to tolerate a different view of the way to use the force. They also sent them out into unknown space in a single ship, that's like kicking people out into the pacific ocean in a tug boat, it's as good as killing them.
Also the Republic committed genocide against the Empire in the Great Hyperspace War. They destroyed an entire species as well as a civilisation. The equivalent would be killing every Prussian after the First World War. Until the reveal about the Sith in SWTOR, the official cannon had them as extinct
. As in no one left, what the Nazis wanted to do to the Jews.
So the Republic is not blameless here.
It is also really dumb to have the Empire as raciest. Because the reason for the Movie Empire's racism was that it was a part of the CORE society. So the Republic should be the racist power and the Empire just a power hungry dictatorship.