I agree if one eats animals has to be able to kill and slaughter, not necessarily it has to be done at every meal but one has to be able to do it.
But the mind is very good at playing tricks... as a friend of mine told a long time ago it is not just because lettuce doesn't have eyes to look into that a life is not taken when you harvest it.
We can't survive without killing, actually we can't even breath.
There is nothing wrong with killing, what's wrong, very wrong, is killing for nothing.
Wasting food, any food, is the biggest crime against life (or God, if you like so).
Like the Kalahari bushman play your dance when you kill/buy your food, elevate its status to sacred because its sacrifice is going to allow you to live, if it is a lettuce or a cow with big brown eyes it doesn't matter.