Heh. I actually called Dr. Joy Browne (radio psychologist- I was at my wits' end) when my first child was about that age and I found myself increasingly negative toward my husband. I told her that I was snapping at him and I had no idea why please help! She asked me when was the last time I got six or more hours of sleep in a row, and I had to answer when I was about 7 months pregnant and didn't have to pee all the time.
Her suggestion to me was to aggressively take time for myself and ignore my husband and child for at least an hour, and to work on getting more sleep. That was when we got the king-sized bed so she could sleep basically in my armpit and I didn't have to actually physically get up and pull her out of the arms-reach thingie by the bed. So I was basically sleeping through all of her night nursing after that.
Between allowing him to work out an agreement with the baby on THEIR terms (previously I had been swooping down and rescuing whenever she would cry, since I had the Magic Boobs if all else failed) and getting more sleep, I became a much more pleasant person over the next few months.
I don't know of a way to translate that into your situation since I was the mom and your ISFJ is the dad, and I suspect you are at least as in need of me-time as he is so I probably wouldn't recommend more self-sacrifice on your part. I guess I'd say just to try to make sure you BOTH get breaks on a regular basis, if you're not already. We forgot about that part.