Right, I think I have a working brain cell now., but I make no guarantees of this assertion
This is why the label "high functioning" can be so misleading. We can be harder work than some children with LFA.
OK, thoughts...and sorry for putting it in quotes but it helps me to think...
"If I stayed quiet, he followed me around and talked, always expecting an answer"
Unfortunately, people can be seen as utterly fascinating toys rather than people. If he talks, you say something. That's all he knows. You having needs doesn't occur to him, and because we can handle up to 100 repeats at a time without any problems, he can repeat a question 100 times without wanting to stop. He needs to be diverted onto something more entertaining than your answers, somehow. That's where an expert can help, looking at his specialist interests and working out how to get his attention fixed on something that gives you some breathing-space.
If he's getting really anxious/aggressive, he needs to be able to learn to find a quiet space where he can calm down. Have you tried a popup tent, a specialist autism weighted vest, etc? Can be very useful as a dark-low-sensory zone and a way of cancelling out the overload for him?
He has to learn that he's not allowed to say that people are 'stupid', or use things like "you don't like me any more". He's looking all the time at your reactions, and if he's getting you to be very animated if he says particular phrases, then that's why he'll repeat it - to see if you do it again. Not reacting is vital. And often just about impossible And him realising it's a bad thing for him to say things like this is vital. Again, an expert to help you work out how to divert that into useful comments so that he learns that better things happen if he's polite? And find safe non-violent ways to dissuade him from trying the rude/aggressive stuff.
As for lists of rules, how about you get him to help make them. If he's not so good with writing, make picture rules. That'll keep him occupied for hours, I'd say. He can invent rules for thousands of different situations, not only in the house, but for school or nursery or shopping or anything else. It's how we learn about the world, so it'll help him to think about bigger and bigger rules until he stops worrying so much about the smaller ones.
He's bright! If it's any consolation, he'll be lovely when he's older, or asleep
but you SO need some time just for you.
Had one like this - once he'd learned to talk. It was a trial!
You are definitely a good parent. This is just autism stuff, not a reflection of your parenting skills. Fear not.