I would also suggest that you not let them free near each other for the foreseeable future. Maybe set up a big crate (or small room) with litter box, food, water - and keep one or the other cat in it. Everytime they have a fight it makes their aggressive behavior pattern more likely to continue in future.
If you are open to alternative treatments, I have had great success with Bach's Flower Remedies with my pets. Choose 2 (or at most 3) of the following and put a few drops of each in your cat's water bowl.
Chamomile: This is a calming remedy that helps fractious and irritable animals. It is especially useful if they are teething and also helps the animal that tends to have terrible temper tantrums. (FES)
Cherry Plum: For animals that cannot control their behavior, such as aggression and biting, and tend to have violent impulses towards other animals and people, and even be dangerous. (Bach)
Vine: This remedy helps with the dominant animal who wants to be the boss of all the other animals and people. They are bullies to the other animals around them and hate to be disciplined. (Bach)
Walnut: This is an extremely useful remedy for any time of transition, such as moving house, becoming pregnant, adjusting to new animals or family members, or going to a new situation. (Bach)
Willow: This remedy helps with resentment and bitterness and often helps cats that urinate everywhere, due to a change in the household, such as the arrival of another animal or a baby. (Bach)
Descriptions from here:
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http://www.petsynergy.com/flower.html#C6>