"If you learn that someone in your life is cool with their government supporting a genocide, you can just sort of let your feelings and natural inclinations lead the way on that."

It is pretty shitty to find out that your bestie (or even just a nice acquaintance of yours) is okay with genocide on any level. Your trust in them instantly evaporates. How can you trust or like a person who is okay with bombing children? With letting newborns die in their incubators after killing the nurses and doctors taking care of them? With burning down tent camps and burning people alive? You just can't trust them or be okay around them any more. A wall has grown between the two of you. It's best to just walk away from the relationship altogether or keep an emotional distance and not get too close to them again if you have to continue interacting/working with this genocide-apologist. But it just plain sucks, no doubt about it.