Coping

My nephew died. He was 20 years old and had his whole life ahead of him. He killed himself. I am beyond grief. My poor brother is heartbroken. I want to write a big long post about it but I'm not sure if I can. But I'll just give some details just so I can remember what happened.
A month ago my nephew went to Bonnaroo, which is a three day music festival in Tennessee. He had gone 2 years ago and enjoyed it and was fine. He went with his older sister. They also had many other friends there. But something happened. While there he took LSD. When he came home he was changed. He could not shake out of this depression. I only found out about this after he died. The depression was so bad my brother had him in a hospital for three days. The prescribed medication and therapy. After three weeks he seemed to be doing better. No one thought anything like this would happen.
On Monday night he came home from work at about 10 PM. My brother checked on him in his bedroom just before going to bed. He was playing his guitar and was on his computer. Everything seemed fine.
A little past midnight my brother was awakened by a phone call from someone who read a post on facebook from my nephew where he seemed to say good bye to everyone. Before my brother and sister-in-law could even get down the stairs of the house there was a pounding knock on the door. It was the police and emergency ambulance. Someone had made a 911 call from the house. It was my nephew's last act. The police found him in the garage. We was gone.
We are not sure how long he planned to do what he did, but we think in was an impulse brought on by the depression. We will never know if he planning for a few minutes or a few weeks. We only know that at that moment his pain was more than he could bare.
I don't understand it. He had so many friends and had so many plans for his life. He was about to finish college. He was a good student. He wanted to go to Italy and was learning the language. He could play the piano and guitar. He was in a band he helped start. He was writing songs. He was learning how to brew his own beer. He had 2 summer jobs. He never seemed like he would ever do this.
I am in shock. I may never get over this.