I do not miss those days! Speaking as a parent with a child like this, just know that it WILL get better. Here are the strategies I used:
"Walk away" -- I would tell him to walk away if he was screaming/crying in frustration and he would go up to his room and calm him down. (That's the good side of ASD -- following rules)
There were plenty of times where I just had to sit nearby and let him work through it. Like that time at a basketball practice where he spent a half hour insisting at the top of his lungs that I couldn't help him tie his shoe even though he'd only let us show him once before.
When he got a little older, we started adding the word "yet". "I can't. YET."
Three years ago, someone clued me into this TED talk on the Growth Mindset.
https://www.youtube.com/watch?v=pN34FNbOKXc
I made him watch it ... a lot! Any time I got the "I can't", out came this link. Then it became a family joke and he now smiles and adds "yet" himself a few seconds after he says an "I can't"