Should I tell my mom my brothers a meth addict?

I have recently learned that my older brother 35, has been smoking meth for the past 2 years.I'm 25 and i always looked up to him so much and to learn this has broken my heart. He's not the person I thought he was.He's bipolar also and blames all his drug symptoms on his mental illness. He treats my mother like a slave. She always gives him money and shes enabling him. He throws tantrums when she cant give him money. My mom works 2 jobs and is very sick. Should I tell her? How do I go about doing this? Shes very touchy about my brother and if we say anything bad about him she gets upset. I fear if I tell her she wont talk to me and ignore me. I love them both but my brother is running my mom into the grave, Please advise me. thank you.