Thanks to everyone for the concern, supportive comments, and welcome advice.
My brother, as you might expect, is still in the hospital, but things seem to be going well for his health overall. I think the healing is slow, and that's frustrating for him, but in a lot of ways he was really lucky. He'll have several more surgeries before he's through, and the therapy will be arduous, but they expect that he'll be able to walk again which is a blessing.
As for me.. they did in fact offer me the position. For slightly more money than I'm making now (which isn't saying much). I spent 5 days crying and wrestling with my options. In the end, the decision came down to a choice between what I wanted to do (take the low-stress student service job) and what I felt I should do (stay at my postdoc and keep my options open for the future).
So I turned down the job.
But... I don't intend for the next year to be business as usual. I've got my feelers out and I've already lined up a few side projects to help beef up my CV and to get some exposure to "alternative" science careers. One editing project, a writing project, and an opportunity to do some work for a tech transfer consulting firm. All of this will of course be done in my abundant spare time (note: italics indicate extreme sarcasm). It'll be hectic for awhile... i.e. I'm actually increasing my stress load instead of decreasing my stress load... but I think it's important for me to really explore my options instead of just giving up on finding a place for myself in science.
Of the many important lessons that came out my most recent semi-annual career crisis (or SACC, if you will): I have a freaking amazing husband. Husband was so supportive, let me talk through all of my worries and stress and never once tried to tell me what to do or to quit whining... He took my concerns seriously. He let me cry it out. He let me scream it out. And with his usual pacific demeanor talked me rationally through all the pros and cons of the 30 different career options I threw at him over the last 10 days. And when the dust settled and I was in (virtually) the exact same position I was before all of this chaos ensued, he brought me flowers and made me dinner.
My husband rules.