I am sorry for your pain, but yes, there is *really* nothing you can do. Except save yourself.
"I don't want to leave her alone. I feel compelled to do something. Anything. I just don't want to do "nothing" about this."
Then you being in pain is inevitable. If you think you deserve a modicum of happiness in this life, then do "nothing." Walk away. Now. And get on with your life.