This exact thing has been my biggest 180. Like Mike said, I too usually reacted almost immediately to things H said...I would have 2-3 sentences out of my mouth well before my brain was fully engaged.
Not so any more. Now I allow myself time to absorb the information, process it and determine what response, if any, is warranted. I am not sure if H has caught on to what I'm doing yet or not-a few months ago I had to ask him a couple of times NOT to preceed what he was about to tell me with "now don't flip out L..." because he was so certain I'd react. I guess he was used to saying that before he'd tell me something he thought would set me off. I asked him to tell me how he expected me to react. And I paid close attention....
I am learning to forgive myself that quick reactionary instinct I had by trying to imagine how I would like him to act that way.
I think I'm getting the hang of it and it seems to be more the norm for me. I am learning that by engaging my brain before my mouth gets going I am avoiding a lot of self-imposed friction.