You did the right thing! I had a professional animal behaviorist tell me that an aggressive cat can always be taught not to attack; but a victim cat cannot cannot be taught how to not be a victim. Cats are opportunistic critters and will attack a victim. No matter how good the training of an aggressive cat, if a victim cat is in the living space there will always be discord. A victim cat will always be a victim cat. My "victim cat" blossomed after the aggressor cat went to her new home