((((((trying & caring))))))
i'm so sorry you had to go through such a frightening experience. you did the right thing in notifying admin, and you are such a caring person for finding this person's number to call and check up on him. it touches me so much that we have people on PC who would do that for a stranger they've spoken to over the net.
just a suggestion (should it ever happen again - here or elsewhere on the web, which i sincerely hope it won't) - is that you call the police/emergency services in your area and turn the chat transcripts over to them. they will have the resources to track the poster down, assess them and provide support if it is required.
it is a difficult balance between being someone who is concerned and desperately wants to help, and also knowing that you need to look after yourself. i used to volunteer for a suicide crisis line (phone & online) and this is what we would do (try to talk the person out of those thoughts, but once it became apparent that the threat was immediate - refer on to emergency services who had better and more appropriate services & personnel to deal with an critical situation like that). there was a case recently where someone in america made a report about someone they were concerned about, and it became an international thing - i think they were able to find & help the girl involved in time, but i can't remember the details of which countries were involved or anything.