I've never been a big fan of international law, because it's basically futile. Unlike domestic law, in which the sovereign state can enforce compliance, international law is self-administered, meaning that it's usually exploited by one side or the other to legitimize what they were going to do anyway.
But, in any case, history is replete with examples of great powers adjusting the borders of lesser powers, usually as a result of conflict or the threat thereof. Kosovo is--and has been for centuries--a predominantly Albanian territory. Had the Serbs been willing to leave it at that, they could have held onto it indefinitely. But they were wedded to the dream of a Greater Serbia, of Holy Serbia, and the Field of Kosovo just won't go away for them. Sorry, but the Serbs were largely responsible for turning the Balkans into a killing field for the better part of a decade, and I feel very little sympathy for them.
As for Georgia not being a "real" country, again, read some history. The Georgians had a kingdom, and were Christian, when the Slavs were still padding around the Pripet Marshes and the Rus were still bashing each other on the head in the backwoods of Scandinavia.
And spare me the pan-Slavism, which is usually just an excuse for Soviet irredentism these days.