Erick, I'm sorry this happened to your dog, really awful. It ticks me off that our dogs aren't even safe in their own backyards.
There are lots of articles that Ed Frawley has written on dog aggressive dogs. If you click on "Search Our Site" on the lower left side of any of this website's pages and put in dog aggression, you'll have many from which to choose. Here's one to start:
http://leerburg.com/articles.htm (different articles with some aggression articles as well).
In some of these articles you'll read where Ed talks about not letting your dog socialize with dogs outside its own pack. Currently your pack is you and your dog, no other dogs. It's basically a matter of desensitizing your dog to the presence of other dogs, not necessarily "socializing" him with other strange dogs (playing together, etc).
There's also an article on introducing a new dog into your already existing pack - "Introducing a new Dog into a Home with Existing Dogs". Something you might want to wait on until you have the problem with your dog under control.
There are also numerous threads giving suggestions as to how to deal with a dog aggressive dog.
If you end up also consulting a trainer, make sure of the trainer first. Qualifications, expertise, etc, and ask a lot of questions before you commit your dog to that particular trainer's methods.
So basically yes, I would try to change your dog's behavior. Do not just throw him into the fray and then try to deal with him. That would not be fair to him. You need to protect him from other dogs, at the same time getting him used to passing one during a walk, seeing one in the distance etc. Desensitizing.
You have to correct his behavior at the moment you sense he's showing any aggression (a fixated look, growling, barking, hackling). The key is to know when your dog is going into that zone BEFORE he goes there and correct him at that moment. You wait even a few moments and he'll be harder to correct and harder to get his attention on you. The correction won't need to be harsh unless you've already let his behavior escalate.
When you encounter another dog, keep moving with your dog. Don't stop. Remain calm and matter-of-fact, all the while keeping an eye on your dog to make sure you catch any change in behavior immediately. When you catch his behavior changing, immediately correct him (use a strong enough correction that will get his attention back on you - it doesn't need to be earth jarring, your dog may not need much correction at all).
Whatever you do, DO NOT take him to a dog park ever. Some dogs may do well there but others suffer greatly for their "socialization" by their owners and their owners don't even notice. I would never take my dog to one and your dog certainly cannot go to one because of his aggression.
Not only do you need to protect your dog from other dogs, you need to protect other dogs from yours.
The key is to get your dog to pay attention to you rather than to the other dogs.
Hopefully some others who have had experience with dog to dog aggression will chime in here. Meanwhile read as many articles as you can.