Sandy - This is serious. Holding his hand, and listening, are not suffcient. If a child admits to being suicidal, and the parent does not get that child help ASAP, in the US, that parent would be considered neglectful by Child Protective Services. I would assume something similar would happen in CA.
I'd suggest starting with his school, since they need to know to monitor him during the day. They may also be able to connect you with a psychologist for him, or your T can help with that. If not, try this link or do some research on your own.
http://www.cecw-cepb.ca/Other/ProvAssistance.shtml
Sorry to be so harsh, but I don't mess around with this topic. Please take care of your son.
emmy