I will know know my name as it's called again

Walking out to my car, I see my mom sitting on my brother's driveway.  I'm so scattered lately I'm lucky if I get more than five steps anywhere without forgetting what I'm walking towards.  I can tell that she's been crying.  She and my brother have an unspoken agreement - she'll do her crying where he won't see it.  I stop and clumsily sit down with her.  I don't really have any words to make the situation any different than it is but hope my presence is enough.  The conversation meanders over the barren landscape like a tumbleweed blowing in the wind.  Apropos of nothing and everything simultaneously, she mentions that I am on my brother's medical power of attorney along with his wife.  She was a witness on the form when my sister-in-law filled it out.  Speechless, tears started down my face.  I knew he signed a Do Not Resuscitate and a medical power of attorney but I had no idea I was on it.  It wasn't ever discussed.  I presume, perhaps with no measure nor confidence of accuracy, that my sister-in-law just figured I was a logical choice to add to it.  I ask her if it's true and she confirms it.  She did not want to be the only one it.  I am beyond touched.  Words escape me.  I may be called upon to decide what to do about my brother.  How to die?  What would he want?  Of course, I've gone over the various scenarios of how the final act of this play could end.  How could I not?  But to be there and be an actor on the stage is so different when it actually happens.