Oh my goodness I hope both you and your dog will be ok. I agree with other posts get him out again as soon as possible to have a positive experience, have a stiff drink yourself so your nerves don't transfer to the dog.
I'm going to post the method I was taught and have used to break up a dog fight when one dog latches onto another, it is not a method for when the dogs are in a mad scramble. If you have more than two people there it is a safe method.
Pick up the rear legs of the dog that has latched onto the other dog then find anything you can to stick into its anus, a stick, a pen or yes, your finger. The dog will let go immediately.
I know others here will go yuk, disgusting, your sick and make fun of this method but being in the middle of a dog fight is not fun and I guarantee you at the time you will just be grateful that you got that dog off yours.
Or of course carry a water bottle with you, especially for a while it will give you the confidence that you need to transfer to your dog.
I hope everything is ok, try not to baby him, I know it will be hard, let him get over this as quickly as possible.