I don't think I have any advice...ds was exactly like this as well and I think what you are doing is exactly what you should be doing. I try to think of it as it isn't my job to *stop* the tantrum but to help ds work through it and learn a better way. And at 5 yo now it has been getting better for a while. It was very tough for a couple of years t here! Hang in there and I think you're doing an awesome job.
I have read lots and lots of ideas of things to try in books like The Highly Sensitive Child and others and, of course, find the best course was prevention. But as to what to do once you see your child has passed that point of no return...nothing worked with ds (well nothing I tried anyway). At 3 she is still very young but I also try to talk to ds when he is calm about better ways to handle things and what he actually might be upset about. But I still wonder how much really gets through at 5 yo. I think the key is just to keep trying.
I have read lots and lots of ideas of things to try in books like The Highly Sensitive Child and others and, of course, find the best course was prevention. But as to what to do once you see your child has passed that point of no return...nothing worked with ds (well nothing I tried anyway). At 3 she is still very young but I also try to talk to ds when he is calm about better ways to handle things and what he actually might be upset about. But I still wonder how much really gets through at 5 yo. I think the key is just to keep trying.