First, I would take Cesar's Sessions. It will help you become calm and assertive and to get your dog calm submissive. Once you learn how your emotions effect your dog, you will be better able to cope with situations when they arise.
Second, I would consult a professional who knows how to deal with aggressive dogs. There is no reason for a dog to start a fight because another dog comes too close. Although the other dog may have been sending aggressive energy that caused your dog to react. You need help to learn to read your dog's body language and react before she starts anything. You need to learn to time corrections and perhaps change the collar you are using.
Interview a prospective trainer and ask to speak to clients they have helped to get a feel for their methods. I know you may have to travel to get to a trainer. I live in a rural town and travel and hour and half to train in another state. Here are a couple of links.
http://www.akc.org/events/obedience/training_clubs/
www.dogpro.org
He shall be everything humanity strives to be: Honest, Loyal, Kind in Heart, and Strong in Spirit. Therefore, you shall call him Partner and Best Friend."
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