Omg how horrible!! I'm so sorry this happened to you. Make sure to take good care of your pinky so it doesn't get infected!
Poor Ranger. I've recently had experiences of my own with other owners who don't have control of their dogs. I think you did the right thing. Shame on that woman for failing to control her dogs or even intervene! Throwing coffee cups!?!? ugh. people.
Perhaps think about only visiting the dog park when the two of you can be alone there? My gsd gets possessive of tennis balls, and since you never know how the other dogs are going to be, we only visit the dp when it's empty.
Well wishes for a quick recovery for both you!