My dog killed my puppy. Can she still be safe with people?

My dog has always been wonderful around people. Not good with other pets. I rescued a puppy to keep it from going to the pound. I watched them like a hawk and they were getting along fine. Then one morning my dog just went off and broke the little innocent puppy's jaw. I took it to the vet, but they said it would be $2000.00 to fix it and she would have to be tube fed. I made the decision to have her humanely euthanized. My dog has always been good with people. I am not sure if I should put her to sleep also. I know she cannot be around any other animals. I would like to hear if anyone can give me any suggestions. Thank you.