How does Jim react when he learns that he has been free all along? Is he mad at the boys? Is Huck mad at Tom for putting his friend Jim through all this?

Jim reacts by saying his superstitions were correct. Jim is not angry at the boys, he is too good natured for that. Huck is a little disillusioned at Tom. It is not apparent so much in the text but he does not trust Tom's sense of morality.