I can appreciate where you're coming from, Lori, but I'd like to offer a couple of things to think about as you consider the things your son has told you about not thinking he can live like he is until college:

Suicide is a major cause of death among teens, and 8 out of 10 teens who attempt suicide try in some way to ask for help. As parents, we cannot always discern the difference between our kid throwing something out into the universe to see if we'll help in time or our kid just going through a rough patch. It isn't worth the regret or grief if we're wrong. http://www.teendepression.org/related/teen-suicide-statistics/

And, second, I also suggest looking into the benefits of behavioral cognitive therapy to cope with the pain, chronic health issues, etc. I have two autoimmune diseases, one of which results in my living with chronic pain. Cognitive therapy is not about marinating in self-pity but about learning techniques that help us cope with things over which we have no control. Jon is right - chronic pain often leads to depression, and not addressing it makes dealing with the pain that much harder.

Just some thoughts to consider.