My new pit bull attacked my other dog and bit me. What should I do?

The first thing you need to ask yourself here is whether or not you believe the bite to you occurred intentionally, or accidentally while you were trying to separate the two dogs. If it is the former, keeping a dog within your home that you only just adopted that is already ready inflict harm to you is going to be difficult if you don't have a ton of experience with dog behavior and training. While I love pit bulls (I have three), I readily understand that they are large, powerful dogs that can do some serious damage. If you live alone, or if you have children, my recommendation would be to relinquish the dog unfortunately, If the latter is what happened, there may be opportunities for addressing the issue. I would keep the dogs separated for at least the next 24 hours and let things cool off. I would reexamine the entire situation and try to identify what could have happened that brought about the fight the first time. Examine it from every single angle possible, in terms of people in the room, dogs in the room, items in the room, what the dogs were doing, anything at all that could be a variable. This is going to be the most important thing to figure out. You will ultimately need to keep Jazzy on a leash until you are completely confident that she isn't going to hurt your little one. The process may not be short and will definitely not be easy. Either way, I am going to suggest you hire a dog trainer and / or speak with a veterinary behaviorist. If this sounds like all too much, I don't blame you. I think that you have not had her long enough where you should feel terribly about having to relinquish her. I understand it is difficult, but this is not a great situation for you or your dogs. I do quite a bit of behavior consultation and I would be happy to talk some more if you'd like. Either way, I hope you are able to come to a decision. Stay safe.