territory

Question
Both of my cats wandered into my life after having been dumped full grown out in the country.  First, a large neutered tom.  A year after that a pregnant, starving female.  I had the female aborted and neutered and hoped the two would settle down together.  They're both indoor cats w/access to outside via cat doors. 18 months later, black tom still beats her up when he succeeds in ambushing her, so she's afraid to go outside to pee, and she snarls and growls when he comes into a room where she is.  Occasionally they tangle in the house.  Each of them individually is very sweet and they're both good mousers.  Why this conflict that seems endless? My friends have multiple cats and think this hostility must be my fault.  What might I be doing wrong?  I really don't do anything other than observe.  Any suggestions?

Answer
If cats are not family, you must trick them sometimes into making them think their related. Some people recommend bady powder that is safe for the cats and putting it on them for sometimes weeks till they act like family. You should talk to your vet about this. Only they can recommend this for a fact. Good luck and sorry. Happy Holidays