I think we need to have a balanced vision, looking from different perspectives: the ones from the EU, United States, Russia and Ukraine to begin with. Negotiating is the answer: yes it takes some time, but it is the best way in my opinion. Don't deny your mistakes, but don't sacrifice your values. Be firm but flexible. And remember the things that unifies us, the best example: sports and culture.
This is all Putin... I don't think one can blame all of Russia because of one man's personal decisions to just attack other countries. Russia is a great country, but it's all overshadowed by a dictator. Similar to my own country.
The few I know about the Ukrainian and Russian relationship during the last century can explain a lot of hate between these two peoples. The catastrophic consequences of the brutal intervention of Staline on this part of the world with a deliberate created starvation, forced populations displacements and mass killing surely let traces in the collective unconscious of Ukrainians. During the History Russians surely killed more Ukrainian than the Americans. Crimea was a motif of war between the two countries but in fact the first inhabitant of this region were the Tatars deliberately deported from their country by the soviet government and replaced by Russians. After that Crimea was given to Ukraine. So we can understand that this place is not very stable all the more with the Putin attitude who seems wanting to restore a new USSR.