Claire - Given that your H seems inclined to overinterpret communications between you I would keep it as short as possible (that's just my opinion).
Something like - I know that D4 is the most important thing in your life and that you care a lot about being a great father. I'm sorry, I didn't equate asking about a jacket with questioning your parenting skills or opening a debate. In the future, I'll be more aware that you may see it this way. Enjoy your time with D4.
