If you just cannot help yourself, I would make a list of resources he can call and send it to him. Salvation Army, Teen Challenge, hospital, etc.
There are other people he can call, it's a choice he is making to call you. If he truly wants help, it's out there. If he calls or texts that he may endanger his own life, send the police to do a well check on him. They do that, and that pretty typically will do two things. If he is yanking your chain, he will stop once he sees you plan to just send the police to well check him. If he truly needs help, they will get the ball rolling when they check him.
Hugs.