You've confused the different groups of BElves. Only the BElves who followed Kael'thas to Outland used fel, some of which reformed their ways under A'dal. The vast majority of BElves stayed in Quel'thalas and didn't use fel. The schism occurred over sucking mana from small animals (it's not like they were vegetarians), not the use of fel.
Also, green eye color has nothing to do with HElf or BElf alignment.
Originally Posted by Blizzard Entertainment