The same as when you help any other cat: the cat has been helped. If there is any effect beyond this, it will depend on the cat and how the cat feels about you. Cats of any color do not have extraordinary powers.
you get bad luck
Nothing happens, except now you have a dead cat. Don't "sacrifice" animals. It is both cruel and illegal.
its really creepy. but its not true
Cry to god for help.
He begins abusing his wife and pet cat
No, however something like a cat who happens to be black IS considered unlucky by some people.
No it is not. A black cat is a cat that happens to be black, nothing more. Because a cat's eyes have a reflective layer, a cat's eyes seem to make their own light at night. This has led foolish people to believe that cats are somehow supernatural, and black cats even more so, only because of their color.
he begins abusing his wife and pet cat
the kitty my go SPLAT! on your tires but hopefully, it never happens
He starts abusing his wife and his favorite cat, Pluto --APEX
Maybe that just happens to be a color she likes. Some people like white or orange.
black cat and the red eyed black cat [only in the japanice area]