Fristly commiserations for your loss.
I have to declare an interest here for two reasons - one is my experience of three years as a Samartian, when I gained an 'intellectual' understanding of the concept of suicide, and the second is a total mental brteakdown which I suffered nineteen years ago, i was in a psychiatric for three mohths, and off work for a year, and i gained a 'oersonal' insight into suicide.
Let's dispel a few common myths here -
suicide is not 'brave' or 'cowardly' or 'thoughtless. It is the act of killing the pain. The suicide has reached a point where living for sixty more seconds is more than they can stand, and death becomes a welcome release, a pleasant alternative, a final chance to hit back once and for all at the torment that obssesses the mind.
The notion of appealing for help - of concern for anyone finding the body - of loved ones left to grieve - all these are rational notions, and the suicide has left these concepte behind a long time ago. The only, the ONLY thing that fills the suicide's mind is pain, unbearable emotional torment, so concepts such as rational thought have long sincec left the building.
Know that there was nothing you could do. Your friend was beyond talking, reaching out, thinking, feeling, loving, and finally living.
It is not something you can rationalise, it is what it is, the end to suffering.
For those left behind, feelings of regret, grief, anger sorrow, frustation, love, hate - these are all the ways in which the rationa mind assimilates loss and grief, but try not to blame the suicide. He did what he had to do to end his suffering, and is finally at peace.
Again my sympathy, but remember, you have the ability to think through what happened and why - something your friend lost way before he finally died.
Be patient, be thoughtful, be positive. Live.