Hi op sorry you are going through this.
First of all, why is his hand-writing an illegible scrawl at fourteen years? Does he have any known learning difficulties? Are you in touch with the school about this? If he has an undiagnosed condition that could exacerbate his anger and frustration,
The son of a friend of mine went through secondary school without knowing he was dyslexic. It was never picked up. Everything went belly up during A levels. So it can happen. And buys can be very embarrassed abs act out to cover up their difficulties.
This needs addressing.
Aside from any potential SEN though, I think you and your dh need to do two different contradictory things now, which is back off and don’t take his rages personally, and allow him to make decisions which lead to natural consequences.
So every time push all the decisions and responsibility back on to him, Choose your battles.
And set absolute boundaries on some key things eg if you talk to us in a disrespectful tone, we will walk away. Never engage in back chat. Don’t explain the new policy. Just walk out every time. Even out of the house if you have to. He will soon learn that to get your attention he needs to remain civil.
An example of natural consequences might be : instead of you and your dh tearing your hair out over his lack of hwk, say something like, here’s the deal. we love you too much to let you neglect your education. We want the best for you. We want you to get a job you enjoy one day that will give you freedom and stability and make the most out of your talents. We hope we can trust you to make the right decisions but we are not prepared to fight you constantly any more.
So from now on it up to you. If we don’t hear from your teachers that you have been putting effort in, you won’t be getting half of your allowance and you won’t be getting lifts and certain privileges.
We will be interested to see the decisions you make. Good luck.
And then follow it up at the end of each half term.