I don't know what I can possibly add to the wisdom that has been given to you already by the great people who have responded so far, but cannot read this without giving some type of reply.
Suicide is hard to understand. Everyone is different, and all respond to stress in a different way. I was almost there myself, (tried but was very drunk and scared, ambulance got there before I was done, courtesy of a best friend I'd called to say bye to) and maybe if I explain a bit you'll get a better glimpse into the mind of people who think that way.
First, when I look back now there was nobody in particular I could blame but myself.
I was in a position that I didn't know how to get out of, I couldn't see a solution that I wanted to deal with, nothing I found tolerable. I wanted peace, nothingness, and the only way I could see that happening was if I was no longer here. It wasn't a particular person, it was a whole set of circumstances all melded together, and I suspect the same was true with your son. Suicide for me wasn't an act of revenge against someone for something they did or said, if revenge or wanting them to feel horrid was the case staying alive and making their lives miserable would have been the better option. Instead, suicide focuses on ones self, wanting to be free of having to make tough choices. Honestly. I almost resented the fact that my suicide might make the lives of people who hurt me more peaceful.
Looking back at ANY of our relationships, we can all find things we could have done or said better, or wish we wouldn't have said, or situations we could have avoided. The thing is, we often can't recognize that until we look back. That's part of being human.
About suicidal people going to hell...the bible contradicts the thought that all suicides go to hell. It does say that unbelievers do, but there is no way for any of us to know the heart of another person. Even if someone's lifestyle seems to contradict "belief in Christ" (and all of our lifestyles do at some point or points in time!) keep in mind that even the thief on the cross was saved. One simply does not know the last thoughts of a person, so don't let anyone tell you they know the final destination of anyone who has passed on.
God has a tendency to understand the human heart and mind, and to think that God reserves his sternest judement for those who are suffering extreme pain emotionally is a ridiculous concept that contradicts the nature of God as described in his word. Please don't buy into it.
Chrys