Peppajay your ds sounds lovely. Your DH, by contrast, sounds horrible.
How dare he dictate from his hideaway, whether your ds should continue his assessments! What sort of a parent is he? One who does no parenting!
That incident over cake on sofa sounds awful. Your poor, poor ds!!
And the blaming and criticising you.........
He is in no position to dictate what happens with your son's assessments. He abdicates that responsibility on a daily basis.
you say he 'cannot cope with the demands of everyday life' except that he's capable of keeping a very tidy house (and presumably a job) so maybe it's just family life that's 'all too hard'. So he takes it out on you and your ds.
I've been there, OP. My ex was hideous to be around. Couldn't cope with family life, noisy, messy kids. Only he didn't have Aspergers. He was an abusive Twunt.
What happens when you stand up to this bully, OP???
Press ahead with assessments, OP. You are doing the right thing by your ds. But failing to stand up to your ds is doing the wrong thing, I think.