If Yanukovych had not been ousted there would almost certainly not be a separatist uprising in the east. The uprising in the east is a direct result of the democratically leader Yanukovych being ousted, he had majority support in the east. This whole thing is due to Washington's desire to get ever closer to Russia and to encircle them (likely punishment for Russia preventing western military intervention in Syria). The EU is also to blame for its continued expansionism.
I know people in Eastern Ukraine also and none of them like what happened in Kiev and they do not like the new direction the country is going in.
Russia is naturally going to support people who are loyal to it, it is next door to them after all and this land was originally Russian anyhow. So one cannot blame them for being involved. They have far more right to be there than what we in the west do to be in the middle east in the way we are.