We had Slovenes killing Slovenes scene after WWII, which is even worse.

What do you mean?

I believe he meant, Communist-Slovenes against Nazi-Slovenes, quislings and collaborators.

Something like that, yes. But there werent just collaborators who were killed, anyone who was considered enemy of revolution was killed. Actualy slovenia is graveyard of europe. There were many people killed by communist's after WWII and there are still many mass graves (pit's, caves etc.) troughout Slovenia. List of people killed in area of modern Slovenia;

Ukrainian Cossacks, Serb Chetnik's, Slovene Chetnik's, Croatian Ustasha's, Slovene Home Guard's, Partisans who were against communism or started to doubt in communism, slovene civilians who werent on any side, people who were better of before WWII (rich, middle class etc.), german soliders, soliders (any Yugoslav) that were forced to go in germany army during WWII, people acused of being enemy of revolution, etc.

There is mass grave near my grand ma's village which few people know about.