Rhap--I lost two older brothers to drugs. One was 38, the other 42. Neither one was ever dx'ed with a mental illness but now that I am look back and after all I've read it is very clear to me that they had personality disorders and were both bi-polar.
Anger that I couldn't do more or that they didn't do more is something I am still working on. One was clean for eight years. Thought he was free. Heroin thought different.
I think being in contact with your brother through email was a wonderful show of sisterly support and I'm glad you had that.
PM if you ever need to talk. I understand.