The attribution of emotions to God has to be understood as a way of teaching us how to behave. Indeed the renowned Kuzari teaches that we cannot really understand what the Torah means when it says (as it does many times) "God was angry". We are merely attributing human emotions to God, Who is obviously way beyond anything we can imagine.
However, by using these terms, the Torah itself legitimizes this approach as being the only way for us to imitate God, have a relationship with Him and learn from Him. So you are correct that God is full of love, but we see in the Torah that He "expresses a range of emotions" according to our human perception.
There is no question that if we want to describe God's feelings towards Stalin, Hitler, Pol Pot, Arafat etc. we would use the term "anger". We too are supposed to feel anger and outrage when confronted with evil. God does not expect us to be devoid of normal human emotions, He wants us to direct them, and to control our actions, but He doesn't want us to be unfeeling.
Of course, behind everything that God does, is His love for us. But if we only focus on that and ignore the other emotions described in the Torah we are in danger of having "sympathy for the devil" so to speak.
Nevertheless, the Jewish people have not been vengeful, despite the enormous suffering that has been caused for us by various nations. Even today, combat soldiers in the IDF, (and I have personal knowledge from two of my sons, and two nephews in the IDF) are not hateful and vengeful people. They would prefer not to fight, not to bear arms. I know relatives of terror victims whose Jewish values urge them to seek peace not vengeance. But I think it is legitimate for a victim of the Nazis or Hamas to ask God to punish them in what the Bible itself calls "anger." Do you really think that God is "happy" with the Nazis, Al Qaida etc.?
