I can understand that. The first time I bought a mouse for a snake, I felt awful the whole way home, listening to it in the box. Same with the first time I fed a rat last week.
Both times, I quickly remembered that it's the natural order of things. I eat burgers, snakes eat rats :) (I don't mean that as an argument that you should feed live, just why I don't mind).
BTW, you know that adult BPs are either rat or multiple-mouse eaters, right?