Hi! You are a sensitive soul, can tell that straight away. Im an animal lover and yes, I get very upset when I hear/read about cruelty to animals but by the same token cruelty to children, the elderly, world troubles - all these things are upsetting. However, it must not become an obsession. The cat will be fine, there are many cats who are housecats and are quite happy. It's obviously loved so stop worrying about that.
I agree with wildwood - think you need a little bit of help so these worries do not take over your life.
Have you also thought about helping out at local animal rescue centres? Im sure they are crying out for volunteers and it could do you the world of good - doing your bit to help, as well as theraputic for you, just think of the grt feeling that you are doing your bit to help.
Just a little thought.x