Both sides, did some awful and unmoral things, but the nationalists did a lot more awful things. Like bombing fleeing refugees. Also, the nationalists ended consolidating around the falangists and pro-nazis ideologies, and getting military help from fascists Italy and Nazis. When we ended the civil war, we had to endure a fascist regime to the end of 70's. And we endure yet some sequels of this.
So, please, don't reduce the civil war as "hate and violence between neighbors in the name of extreme political ideas". It's was an bloody military uprising against the legit government that the people elected, that ended with fascists on power.