Please don't pay any attention to the criticism posted in this thread. Having only read a few of your posts I know you're compassionate and care deeply about the animals and people in your care.
As a horse owner, previous BM and current BO, I understand (as perhaps owners do not) that as the BO, along with the sorrow and feelings of helplessness come horrible feelings of guilt, misplaced responsibility and a lot of "what if?"ing.
Sounds like you were attentive, responsive and did everything to ease this for horse and owner.
When you're feeling up to it, I will PM you the funniest/worst dead horse story I know....