What can I do for my best friend?

My best friend is adopted and his mom is terrible. I mean she feeds him, and clothes him, but she's terrible. I mean his family has money, money enough to buy their daughter expensive clothes, but they buy his clothes from thrift stores for a dollar. He's an extremely talented musician but his mom is constantly telling him she won't pay for his college, even if he gets a scholarship. He goes constantly neglected, not unfed neglected, but his family has two other kids who get 95% of his parents attention. Today she told him she should have never adopted him, and that she should have left him with him whore mother. (His birth mother died three years ago and he's sensitive about it) She's driving him to depression. She can't just do this to him can she? What can I do?