Your entire post screams "Aspergers Syndrome" to me. These are children and adults who are often academically brilliant but so socially clueless that it impacts their lives to the max. I can't even think of anything else to say. Will he allow himself to be tested by a neuropsychologist? Very bright Aspies are often overlooked by psychiatrists because it is a neurological difference rather than a psychiatric problem (although it can mimic one and can be misdiagnosed).Your therapist should NOT have diagnosed a person he has never seen. My son, who is on the spectrum, was wrongly diagnosed with bipolar and put on medications he never needed. Psychotic? How? Psychotic means he is out of touch with reality. I think your therapist, since he is a therapist, never met your son and is not a neuropsychologist is looking up the wrong tree. BE CAREFUL!!!!!!!! Yikes!
I am a lifelong psychiatric patients and it is hard to get the diagnosis right even when you see the patient let alone just by listening to you describe him. Not to mention, therapists are really not allowed to diagnose anything because they don't have the training. Your therapist may be good for you, but he is not aware of Aspergers...a common problem...or he would have at least mentioned it with your son's particular problems.
When your son said he was "socially retarded" and did not fit in, my heart started beating faster. I have a son on the spectrum. That's exactly what Aspies are like. And they don't "get" people at all and people often find them awkward and strange. There is tons of help for this, but he needs a diagnosis by the right type of professional. You CAN teach bright Aspies to live and function in this world.
Without treatment though, Aspies often fail. What was your son's very early years like? Was he extremely precocious? Speech delay or just the opposite? Obsessive about his interests? Few interests, but very intense? Inflexible? Scared of or unable to transition well from one activity to another? Extreme perfectionism...things had to stay the same or he'd meltdown? Either shy or just socially inappropriate, such as running up to another kid and sticking his face into the other kids face and starting to monologue about his interests. Inability to have a give-and-take conversation? Onesided monologing? Able to recite television commercials or shows back to you verbatim?
There are lots of traits. I think your son diagnosed himself. Normally I tell mothers of adult sons to let them learn to be independent, but I'm not sure your son can do that without outside help. He seems to know that he is different and would probably be maybe relieved and eager to help hiimself if he could only get diagnosed. These young adults often do not learn by watching others. But some do. My son, who is a step below an Aspie, has learned A LOT and is far more "normal neurologicallyl" than he used to be. But, then, he's been getting help since toddlerhood. Your son is so bright that everyone missed it, I think. He was probably "differently wired" from the time he was born...maybe started struggling socially early on.
Of course, I could be wrong. Don't take anything verbatim. But do check it out.
Good luck, hon. I think your son will be ok.