Not to jump on the bandwagon, but (1) your professionalism is something to be admired, and (2) whatever he does going forward is absolutely N-O-T on your head. Never steal a perpetrator's guilt! It belongs to them, not you.
What I wanted to add is, let's say you let him die. What then? All it would likely do is eat you up, because (1) you'd know you didn't live up to your pledge, and (2) you'd feel like you were his judge, jury and executioner all rolled into one. I know you would never feel comfortable living like that.
I'm glad (but not the least bit surprised) that you did the right thing and adhered to your professionalism. For what it's worth, I truly feel you did the right thing and will feel the same way in the long run.
If you have to rebuild yourself from the ground up, you get to do it the right way this time. And YOU'RE the builder.