Interesting, I had a conversation with a friend from Croatia that mirrors what you said. You know any decent books or websites that discuss that Orthodox vs Catholic tension?
I suggest “The Orthodox Church” by Timothy Ware (now Metropolitan Kallistos) and “The Romanovs -Autocrats of All Russia” by W. Bruce Lincoln. Most decent libraries will have books that cover the general history of Europe during these periods. If you want to go waaay back you can also read “Byzantium” (three volumes) by John J. (Viscount) Norwich.