I am the sibling of an alcoholic so may have some experience to share that you might find useful.
First off I want to say that I am sorry you are going through this; it sounds to me that you have gone through some difficult family times in the last few years.
Just for a bit of background my brother is 5 yrs younger than I am and it was just the two of us. Actually, it was basically just the two of us from the time I was 21 and he was 16/17. My mother died then and my dad just fell even more into an alcoholic haze. Anyway he and I learned how to take care of ourselves quickly - apparently for him that included a lot of drinking and drug experimentation. I figured it was just youthful experimentation - besides I was busy just making my life work.
Roll forward many years and at age 48 my brother almost died from pancreatitis. I had absolutely NO idea that things were that bad.....in fact if you had asked me if he was an alcoholic I would have said no. We have always been close.....but for years we have lived a good distance from each other so any interaction he could control - timing and level of intoxication.
So....I sat in a hospital room with him for about a week and watched him hallucinate, lash out, almost die, beg for drinks and eventually agree to go to a 30 day rehab. (that I paid for). He went to rehab......I made an appt with my therapist and starting reading Al-Anon materials! He left a week early - I got paid back about 3/4 of the cost and I began the process of grieving for his eventual death. I have no delusions about his prospects of success. I also have let go of any involvement in the process. I Love him a tremendous amount, I talk to him when he is sober, I support any attempts he makes at staying that way with everything but money - but I stay out of his way and detach when I am uncomfortable with his choices.
It has been 2 years now.....and for the most part he is doing well. But...I am doing better for having learned how to separate with love and how to maintain a relationship with him that is healthy for me.
You do not need to cut your brother out of your life. You can control how you let him in by establishing boundries. These are things you do by yourself and for yourself - they do not need to be communicated to him. Sadly - while in active addiction he probably won't even notice. When he is in recovery he will appreciate your trusting him to take care of his own life.
Hugs to you....I know it's hard.