Preventing outbursts is a good start, it prevents your dog to practice (and get used to) this type of behavior. You could use a yellow leash and/or collar. A lot of dog owner will know what that means (https://tractive.com/blog/en/good-to-know/yellow-ribbon-dogs-collar-mean).
But first of all, you need to start a desensitization training, preferably with a dog trainer. During these training you need another dog and you practice to get close to it, but stop when your dog shows signs of stress. Eventually you should be able to get closer and closer without outbursts. Keep in mind that this process is very slow, do not rush it or you can start from the beginning.
Reactivity can be "cured" with time, dedication and consistency. Don't give up.