A family of addiction

My mother was an alcoholic for 25 years +. She drank when she was pregnant with me, and I never knew her sober up until the day she died from liver failure at 48 years old. Her being an alcoholic, she was never taking care of my brother and I. I watched my little brother. I made sure he ate, he wasn't thirsty, cold, scared...unfortunately we were always passed around to babysitters and one of them molested and mentally/physically tortured us for years. I started going to therapy and doing specialized treatment for PTSD about a decade ago. I still struggle, but my life is much improved. I am able to make much more rational decisions. Yesterday a friend called my husband and I and told us my brother is drinking "just like his mother did," and is spiralling. We both called him and he told me he shakes and hallucinates when he doesn't drink. I am so worried for him. I try not to get too wrapped up in it, becuase I have children and my husband, and I also don't want to become co-dependent. My brother doesn't understand this, and thinks that I'm abandoning him. You can lead a horse to water, but you can't make it drink...is what I keep thinking. I'm not sure what to do. If he doesn't stop or get help I know he will eventually die.