Funny people getting frustrated with us isnt it? Yuo cant help how you feel and you arent really asking for help with that, just journalling a difficult journey.
I like your plan with the kids, my BFF (single Mum) is doing the same as you, less PC, more outdoor things, better meal schedule, she feels good about it too, time to focus on them more, they are calmer as a result (so less need for shouting!). Hey you are only human, my BFF gets frazzled too, like when they wont get ready for bed and you are effectively a single Mum as he isnt really helping out in that dept. is he?
Theres that aspect too, he's not just failing to mend this R, he's also perhaps not making the right effort as a father (only 6-10 hours a week, right?). I believe you that he is this way (closed off, lacking in joy de vivre) in all areas of his life and it isnt just specific to you, or your R. Have you tried to tell him your observations of him and how you dont really like that he is that way..and have you asked him why? Have you said, I have noticed you lack enjoyment of life, friends, hobbies.. are you ok? Are you happy and fulfilled, outside of work? How about taking an interest and asking him if he's ok?
So.... what is your gesture for today? (maybe it could be the above suggestion to ask him about himself, if you cant think of anything else!) xxxxx