I think your husband need to give it some time. If your son is depressed, then I think your husband needs to be a little be more sympathetic towards him, and understand that it's not something you can 'get over', and can be a seriously disabling. The agression from your son is typical of someone who is suffering from depression.
I think you and your husband should wait it out for a couple of months until the counselling sessions are well under way, and take it from there.
I understand that it is an awful situation for you, but your son is ill, and getting him to move out and live a new life may not be the best thing right now.
How far does his nan live from you? What does he think about moving to his nan's?
Maybe this would help you and your husband
http://depression.abo...facts/a/howtohelp.htm