two cats fighting

Question
Hello we have two cats. One has been in the house for almost 4 years. The other was a stray kitten we have had for the past 2 years. They are both indoor cats. They always got along fine unitll the other night when the new little cat got scared about another cat walking around outside and attatcked the older big cat.

Since then the big cat has been very vicous and has spat and hissed at the little cat. We have been keeping them in separate rooms and playing with them together. My wife is extremetly upset about this. What can we do to for the cats to get along again.  

Answer
Time is your best bet.  You're doing everything properly.  Give them at least a week of separation, and then see how it goes when you reintroduce them.  Generally, within a couple weeks, they'll have put the traumatic experience behind them and come to accept each other again.

Sometimes when a cat becomes extremely worked up like your older one, he may need a day or two on a medication such as Valium to relax him.  This would need to be prescribed by a vet, and only after giving them time to relax has failed.