I am so so sorry to hear that you lost your mare. Sometimes it seems it's just out of our hands. At least now she's at peace with her foal. I'll be praying for you and your other little ones.
What a shock that must have been to find her like that. I'm so sorry.
I have a foaling chart in the barn that shows a pictures of "bad" things that can happen. One of them is after a difficult birth they get a hematoma on this large vein that is in the pelvic area and if it ruptures they bleed out. I suspect that's what happened to your mare.
I have been in those shoes just this past Jan., with Miranda. It is a total shock that is very hard to swallow, especially like you said, you thought sooner than later. Time passes and we think all is fine. I sooo wish that they could talk to us....Hugs to you..
I'm so sorry for your loss, seems like things just snowball sometimes. We had a year like that in 2007 where we seemed to lurch from one crisis to another.