OP, reflect on yesterday and exactly how he behaved and treated you.
There really is nothing to grieve here.
He is angry at you because he knows he has agreed to what you want and he would rather you stay and be his emotional punching bag.
There is nothing you can do if he refuses to speak.
Carry on with your plans.
Focus on accommodation and tell him X is happening when you have a place.
Allow him to ignore you. His choice.
Stop trying to force him to be a decent human being.
Your son will accept this, he is young.
Mum and dad have decided to have a home each and we both love you.
On a loop.
Keep things very, very simple for him.
You cannot fix this and you cannot fix your husband.
The sooner you accept this and focus on getting organised the better.
It doesn't have to be a long term home, just one that gets you away from him, so that you can breathe.
It sounds like an awful atmosphere and one that it will only be positive for your son to be away from.
Reach out to friends and family for support.
Keep posting and try and be kind to yourself.
There is nothing to be gained by blaming yourself for this situation.
You cannot fix him.