Welcome here to the Forum, it's a pretty good place to come for advice, and trying to look after a son who has depression, anxiety and anger problems is a very hard thing to do. As you would know there is no frame of reference, no way to know what to expect, and sadly no guide book as to what to do.
Smashing, punching, and attempting self harm are way beyond what one should expect and really need professional help to counteract. I would imagine your son is already under treatment for the anxiety and depression, his medical team really do need to know about the severity of his reactions.
For a job interview to fall though is very disappointing, though I'd guess from what you said you might suspect your son never made the appointment - my apologies if I'm wrong. Either way your son has to be able to cope with such difficulties.
Yes your son is there, just as I was, however it's masked by the illness which is very real. A most worrying and upsetting thing for you.
I'd like to ask about your support with all this pressure. Are you all alone trying to deal with all this or do you have family and friends to give you care and support? It makes a world of difference.
It would be realy good if you could come back and talk more