My brother may be too good to be true?

Instead of cutting him out of your life, talk to him. He's probably messed up from the abuse he received as a child, and he must be thrilled to have you as a sibling. The perfection thing must be due to his abuse and he could think that if he does something wrong, he'll be completely alone. Help him by talking to him and posssibly getting him to visit a psychiatrist. I really do hope things work out.