See, the nazis, commies, and eugies, weren't wrong or evil because they didn't follow or listen to empathy. They were wrong and evil because they were wrong.
Nazis use of hatred to gain support may have earned them what they needed in the short term, but the world didn't react well to them trying to take over, and the response lead to germany being worse off than it would have been should it have just stayed in it's borders, built up, and avoided genocide.
Communists use of murder and fear to stay in power is textbook example of how not to stay in power. Everyone knows that you will fall if you try to stay in power using those techniques.
Eugenicists turned out to also be wrong. Diversity in a species is incredibly important and essential for survival and success.
Had they been right, they wouldn't be regarded as evil. They would be regarded as heroes, and likely could have won the fights they fought. The world would have followed the system that lead to better results.
Turns out that when you treat people well, let them be free, and support those around you, you succeed.
Empathy, just like anger or pride, can lead to decisions that are misguided, wrong, or ignorant. Look at vegatarians after all. Look at how many people dedicate so much of their lives to "helping people" to feel good without ever stopping to think of if what they are doing really is helping anything.
Moral of the story is, do what is best, not what you feel is best.