I think what you should do is sit down and talk to your brother about it, because obviously it bothers you. But for now, I wouldn't tell your parents. I know this sounds wrong, but it was one time, and he got home safely. But what you really need to do is sit down with him and explain that he defintely never needs to drive home drunk again. Tell him what it would be like for you and for your parents if something had happened to him. I wouldn't get him in trouble over it, but I would defintely talk to him