By now the crisis will have probably past, but in the future you will have to take
suicideSuicide and suicidal behavior talk seriously enough to have him evaluated by a professional if it continues. Teenagers lose their perspective about these matters easily, and can be very impulsive, as you know, so give him a lot of love, remind him of a full life he has ahead of him, but keep alert in case it turns serious.
Is his father around? Was he a child of divorce or death? Did he have anything semi traumatic happen when he was younger? He is missing something within himself; that I know for sure. I have behaved the same way in the past. (I'm a woman in my mid 20's & i have had alot of therapy to control these feelings; it's gotten better but will always be apart of me.)
I think that the valium was a smart choice for temporarily relaxtion. However, there is something much deeper going on & he does need professional help. Stay strong. You are doing a good job.