I feel your tired aching bewildering pain! You are exactly right knowing it is "normal and to be expected" doesn't make it not hard...it is HARD! and acknowledging that is huge! ...one day at a time...pace yourself if you can. I echo anna's comments there is no guilt (well, there is at first but, it fades) in taking time away with the others who need you (your spouse and other children) and the break will increase your stamina for the coming days. It is so tricky to find the balance. You
will find it through time and repeated good moments. It sounds like she is grieving hard for her foster mom. (a good sign that she misses her--but SO hard for you!) Don't worry about that house or laundry...it will still be there tomorrow
--any neighbors or friends around to help with that? YOU ARE DOING A GREAT JOB AND BEING THERE FOR EVERYONE AND RECOGNIZING WHAT YOU NEED TO DO!