Right, first things first:
This is all so intense, and your DH can cope much less/worse than usual because you're all on top of each other. This won't be the case forever, but it's creating a lot of tension now. Particularly because DH isn't getting his usual space/time out.
A lot of men are not great with smaller kids. Especially the first time round. They tend to want to order the kid around, criticise and make damn sure he's going to grow up how they want. And they really slope out of the boring routine care stuff.
But when the child is bigger and easier and they get more back, they start to like having a kid more.
It strikes me your DH is one of these, and also just deeply angry and worried and disappointed that his son is small and seems to be very sensitive and may have SN. Your DH cannot cope with this. He actually needs some serious support. So he can behave in an acceptable way around your son and you. Because you're right. He can't be allowed to talk about and to your son like this.
For now, I think your only option apart from leaving is to do something different, because the current way you're all behaving isn't working. Your DH seems no more capable than his little boy of behaving differently, so in all practicality, it's up to you.
I would:
Set your totally justified resentment, dismay, hurt and exhaustion to one side for now. (A big ask, I know, but the pay off is worth it.)
Decide that your strategy now is to ask nothing of your DH apart from, eg, taking your son for a walk in the pushchair for half an hour or so on Sat and Sun. Tell your DH you've had a think and yes, it's all been too much pressure, and you just need him to agree to that. (Tbh he should do Sat or Sun morning routine, but not if he's going to be mean to your son).
Then you have effectively taken over. It's agreed. It's your decision. And you know you're only doing this for now, for the good of you all. You're being the grown up.
So now you expect zero from DH except the two walks. So you stop feeling angry when you don't get anything. Because now you've ordered him not to do anything. That feels different.
Now: you can make the day with your son a whole lot easier too. My advice would be:
Go through the whole house - any area where your son is - and pack away or put in a closed room anything at all in reach that could cause trouble if he got it. No bubbles in reach. No nothing. (This is something we all have to do periodically, as they grow - we have to adapt the house to their new skills.)
Next, seriously read up on how to tempt fussy eaters. Try a new thing each day or couple of days. Find more of a range of food. And don't worry if you can't. But there must be and will be some things.
And pace yourself. If DS is asleep at 7, go to bed yourself at 8.30/9. Pamper yourself. Nice bath. Good series. Whatever you like. Ignore DH. Have chamomile tea and go to sleep by 10. Then 5.30/6 won't feel like you've lost out.
Pace yourself. Make your son your job. Nail this. You do it. DH, at the moment, is incapable.
Just make life bearable. Better.
And then when you go back to work and DH goes back to work, ease up your own lockdown regime and see if DH can do more.
Right now you need to make life better for yourself. And be there for your son. Withold judgement on DH. Tbh I'm only saying that as he clearly can't cope. But if he gets support and is still so awful, then I'm afraid I'd be ushering him right out the door. And don't be afraid to do that. Ultimately it sounds to me like that will probably be best. Not least because the verbal abuse will be so damaging for your boy and you can't allow it. Your son is utterly precious and nobody gets to talk to him like that, or think about him like that.
But right now, I'd say defuse the situation and take the pressure off.