Hi i'm looking at it this way , if he has done it once he will do it again , Can't you talk with his Doctor , Tell him/her he is a danger to himself , the Dr can give him a Section under the Mental Health Act for his own good , Hope this helped Please let us know how you get on , take care
My thoughts on this are after the fact,since my son was behaving exactly as yours is.Whatever you do,please take it slow with him and let him know that you are trying to understand his feelings,(even though no one can,but him)I have learned the hard way that the more pressure you put on him,the harder he will try to escape.Mine did escape 4 times and now I don't know where he is.So take tiny steps please.I see that this was back in Feb.,so I hope you made progress,I did the wrong thing and am still searching for my son.Also since he is over 18,he can take you off the list of contacts,and if he does go for help,you will not be included,(and not knowing is horrible).Good luck and please respond if needed.
Sorry to hear about your situation. The best thing you can do as for now is to make him see a mental health doctor. Psychiatrist or psychologist will be able to pinpoint what exactly is he suffering from.
Once a diagnosis is presented you can start with treatment. You have to be patient with him and take things slowly. It would be difficult but I know your son will overcome his condition.
Give him all the support that he needs. :)