I'm split on this.
I completely understand how difficult it is being what is essentially a lone parent to a SEN child (I was the sibling to my severely autistic brother and my mum looked after us both on her own while my dad worked 18 hour long days as he was self employed). I've seen it my entire life, how difficult days can be. How lonely they are. How you never get a minute to yourself, constantly needing to supervise, etc. The thing that helped my mum the most was when she finally got through to my dad that work needed to take a cut and he needed to be at home more. She is currently at home with him every single day because he cannot go to the adult day centre he usually attended from 9-2pm. It's bloody hard work.
Your husband working 8-6 shouldn't be a problem. However, he does need to be fully on board after 6pm. This isn't an employers problem in the slighest- his hours are incredibly regular and he'd be working them regardless of CV19. Stop re-directing your anger onto the wrong people.
However, as tough as it is, you do need to try and help yourself, here. This could go on for months. You can't be struggling this much every single day because you will have a breakdown. You need to try and find a way to make the day manageable. A routine which means you aren't just counting down the seconds until you get a break.
Unfortunately, having a SN child is something that often becomes harder as the years go on. Especially with autism. They get stronger, the tantrums get worse and things go from 'easy' where you're able to cope with a 2 year old, to incredibly tough when it's a 14 year old lashing out at you instead. As I said, I completely understand how tough it is, but it isn't going to get easier. You need to try and seek out support that helps you learn how to cope better, rather than always relying on other people to take the pressure off.
I say this because, and I don't want to sound horrible, but from your posts, your husband doesn't sound particularly happy in the relationship. The things he's said to you are vile. I'd be wary that he might not stick around because someone who is truly in it for the long haul just wouldn't say things of that nature to their wife. You might find yourself in a situation where you don't have him to rely on.
Your husband is the main issue here, but from the little you have said about him, I'm not sure I'd bank on him stepping up. So, I do think, ultimately, your priority needs to be seeking support for yourself on how to make it easier for you to be a lone parent. You can't force him to change, but you can make changes to help yourself.