It so stinks having to be in charge of your parents like that. I totally understand.
In my parents papers I've been put in charge of any end of life decisions for whichever parent outlives the other. And before my dad had open heart surgery three years ago, I was the only one to ask him what he wanted done if he didn't make it out of surgery. (He was out of the hospital in record time.

)
Don't hate yourself. It isn't worth it.
*Gives you a cherishing blondie-bear hug*