Why do you worry about being the 'bad guy'? Why do you have to placate a brother who is using you to keep his addiction going? He's a grown up, able to look after himself. Why do you need to be nice? He's an active alcoholic. He will be very, very good at blame shifting. Being 'nice' gives him a way of keeping you where he wants you. No matter how 'nice' you are, he's always going to blame you. Accept this and you might find it easier to ask him to leave than you think.