I find it hilarious that you apparently can't read a map!
Russia was in no position to aid Yugoslavia militarily. What they did was broker an end to NATO's war against Yugoslavia which retained Serbian sovereignty over Kosovo. (See UN resolution 1244.)
The failure of the West to live up to that agreement infuriated the Russian, they are now simply playing by the new rules!
Sorry, Serbia should pick its allies better. You picked the losers of the Cold War.
The New Cold War result will be the same. Yeah, I used to be against Kosovo independence. But the new Russian reality has me for it.
Russia is an enemy as is Serbia now.