I hear you and I’m sorry for what you’re going through. I dated someone in college who turned into a heroine addict. It changed him completely. He lied, stole, cheated and made his next fix his sole purpose. It broke my heart, but I knew I had to leave him.
Several years later, he turned his life around, got clean and had a family. I promise you, the person your brother has become is not who he really is. Addiction changes people. I wish you the best and hope your brother is able to get clean one day.