OP, I really sympathise for the situation you’re in.
I think from what you’ve said about his childhood, he’s very likely ND and perhaps ADHD as well.This is just going by my experience.
My Ds is undiagnosed Asd. Did really well at school, got good results but in his very last year doing advanced highers he just suddenly packed it all in. Took to his bed and did nothing for the next 5 years. Despite offers to help. Saw psychiatrist who said it’s likely Asd and co morbid anxiety/ depression.He wasn’t offered treatment and probably wouldn’t take it anyway.
I’m lucky to have another property and he has just moved into that. He says not being around people seems to help. He’s getting himself sorted now, slowly.At least he goes out, does own shopping, cleans the place. Next step is a job.
DD also had issues once she left school. Would sit around all day, messy room, no confidence, wouldn’t go out without me accompanying her, poor sleep.
There were issues with her school work and was often off “sick”.
Camhs were rubbish. School psychologist didn’t pick up on anything.
We went private and she was diagnosed ADHD. 2 years on meds now and her life is turned around. Has a good job, boyfriend, very confident etc. Still messy but that’s ADHD.
Your boy has some issues. Tell him you love him and you’re proud of him and leave it at that to start with.
I’ve been through the anger and frustration you’re experiencing. But I found that showing anger would shut them down or cause a melt down. It got us nowhere. It pushed them further away.
Unfortunately, for me it meant ignoring the effect of the condition( messiness, ‘laziness’, sleeping all day) and finding a time for calm rational discussion when they were feeling able to engage.
Your boy’s aggression could be a panic response from anxiety. The messiness from possible ADHD and if he’s Asd as well that’s a double whammy for him ( and for you).ADHD causes lack of focus… possibly the reason for not doing well at school.
I understand how frustrating it is for you. However, if you’re constantly showing anger, it will push him away.
He needs you to not judge his failures which he’s well aware of. He needs you to love him for who he is… unconditionally.
Unfortunately this is going to take some time.
You will need the patience of a saint but good luck.