You are right "I told you so" does not help many situations. He shouldn't have said it.
That said, you haven't been exactly helpful either (as you've admitted)- telling someone they are talking bollocks isn't really likely to pull him round to your way of thinking either. Losing your temper is also unlikely to help.
I also think the mentality of "my way" vs "his way" (with the conclusion- quite possibly correctly- that your way is by far the better and all/most of his thoughts/feelings on the subject are incorrect/"bollocks") is probably not helping much- it is an almost constant "I told you so" to him, IYSWIM.
It's sort of an adversarial approach, which pits one "side" against another. I could be wrong, and it's just the way it's been written/the way I'm reading it- but you do sound quite dismissive of his approach (with reasons, I understand that). As you don't like it when he says "I told you so" to you- I think you can bet he doesn't appreciate it either. I think, in this instance, you are both in the wrong. Although in the wider scheme of things, your DH should be taking on board what is working and going with that, and also taking suggestions from support groups and professionals.
I'm not minimising how hard it can be managing a child with your DDs difficulties, especially when one parents way of managing things isn't helping. I'm not saying your DH is right in his approach- if "your way" of dealing with things is getting positive results it would seem your way is indeed the better way to do things. I am just trying to suggest that this adversarial way of thinking about whose approach is the "right" approach probably isn't helping much either.
Lastly, I think you are both under quite a lot of pressure, things are hard- I'm not surprised tempers are short. Be kind to each other if you can (easier said than done, I know).