Mgran....sorry to hear than your son mentions ending his life.....strangely, when I was a kid from the age of about 4, I used to ask my parents why I was here and what was the meaning of this, and seeing as I had no answers at the time and could not complete the 'equation', I told my parents my existence was pointless unless there was a reason for it......and the reason had to be tangible...... so they bought me a university text book on Biology

(Sorry, not to make light of it......bit of a morbid sense of humour). It didn't answer the question, but for a time it explained why I existed.
As for thinking that you are a robot, I thought the same of my parents. especially my mother. I used to think that they were droids or something and I do remember feeling quite terrified. I always wanted to be a robot. Mind you, my mother terrified me, which is not the case with you, I am sure.....
Is your son getting help in understanding why he thinks the way that he does? Sometimes projecting a inanimate object (like a robot) on to another person can help understanding of that person. I am 38 years old and I have been doing it all my life. The difference is that now I know when I am doing it.
Take care......sorry if I went completely off tangent but when I saw the word 'robot', I couldn't help myself....
Michah