I am so sorry you are going through this. My heart is crying out to you right now. I have also been through what you are going through with so many friends, boyfriends, brothers, etc. My "little" brother started doing alcohol and heavy drugs at age 12. He progressed to being a drug dealer by high school. He became addicted to prescription meds at 23. He could eat 25 Percocet at a time and hardly feel a thing. At 38, he finally got clean after two years struggling; but then he, thankfully, found God and he is doing well now.
The best advice I have for you is go to Al-Anon. It worked for me, saved my life, and put me on the right path in my life. They are wonderful people and it provides incredible social support. Take care of yourself, please.