Hi Trey,
I'm sorry that all of this happened. It is unfortunate that he had issues and felt the need to turn to drugs to solve them. It sounds like he struggled a lot with his demons.
As for how you feel? It sounds like you are overwhelmed with emotion and are trying to comprehend what happened. It sounds like you are maybe looking for answers that you do not have at the moment?
Try your best to find ways to distract yourself, be it a movie, Netflix, YouTube, drawing, coloring, etc.. All of this happened so quickly that I can imagine no one would have answers right away. That's why I think distractions are the key.
Good luck.