I understand where you're coming from because I'm a soft hearted guy who loves animals myself but, as pointed out by others here, animals kill each other to eat and sometimes even to keep things in balance like when lions kill the cubs of cheatas. There are even animals who kill in cruel ways, ways so cruel that I will spare you the details, also there are some animals who will kill humans at the drop of a hat and proceed to feast on them. As Artchic528 pointed out, according to evolutionary science apes began to eat meat because it was something they needed to survive. Biblically in the book of Genesis it is made very clear that animals and humans were originally supposed to eat plant life but, this changed later and now most humans are omnivorous. I think that what is really going on here is that you're tormenting yourself with these thoughts. "Yes" the corporate food industry uses cruel methods in processing meat products because it's faster for them to get things done that way but, farmers who sell directly to the public are usually merciful in their killing methods of livestock.
It has also been pointed out in the past that if humans stopped eating animals then, the earth would become over populated with animals.
Again, I understand how you feel about this but, sometimes things just have to be the way that they are. It helps to choose to not think about it so much. Let it go.