Sorry to hear pal. My condolences for your loss. I had the same thing happen to me over twenty years ago, lost a really good friend, to make it even worst we had words which turned into a scuffle the night before he took his life. There is no explaining it. I have been asking myself the same questions your asking over this period of time. I explained it to myself that apparently he was hurting and just wanted the hurting to stop. I know none of this helps. You just have to have faith and pray for strength. Be thankful for the time you had and how your friend enriched your life and those around him while he was here. I will keep you and his family in my prayers.