I am so sorry this happened to you and Olivia, but glad to hear Olivia will be OK. After this happened to us, Fletcher, who wasn't great with other breeds before, became much more leash aggressive. Some dogs become more fearful. The best thing you can do for your dog is to try and have a positive, upbeat attitude, and not tense up when you see other dogs. I sat "try", because I know how difficult that is I think a stick is probably the best defense, one long enough to keep some distance between the other dog and you (if possible) The bad thing about sprays is, they can blow back in your face, or your dog's. I have yelled, stomped my feet, even thrown a full bag of poop at one dog You do whatever it takes, but, as you know, everything happens so fast!
I suppose it is too much to hope the other owner offered to pay your vet bills