So is it the use of weapons of mass destruction that makes someone "evil"? Were the people who helped him along the way also "evil"?
I honestly do not understand this term evil. Are you saying that he is a psychopath? For me the question has more to do with how many people will be killed and by whom. As I think of war more like a disease. Assuming you are right what is the best course of action right now? I don't think all out war is necessary at this moment.
Did you know that when he used that gas the USA continued to supply him with more WMD? Did you know that in 1989, after he gassed his own people and Iranian soldiers, George Bush41 signed NSD26 saying Iraq is a good country and we will normalize trade with them. Did you also know that in 1989 we trained Iraq nuclear scientists in how to blow up nuclear bombs?