However you work this, Lara, please be compassionate toward yourself. You suffered a tragedy with the untimely death of your brother, and such events make us very vulnerable in so many ways. We are weakened, more susceptible to suggestion, we intuitively feel we cannot bear any more pain or terrible revelations so we defend against anything which might hurt us again and this can include our own logic.
Whatever work you do around the issue of H and his drugs and behaviors, do not hurt yourself with what my counselor calls the "inner persecutor." It can send you into shame which you do not deserve and which can drain the life out of you. You are a good, a beautiful person who has experienced profound loss in her life. If you went off track at anytime, it is because you were wounded, not crazy.
God will reveal to you what you need to know when you are ready to know. Try to trust that.
You are worthy of a happy life and healing.