It sounds like you have a nice dog that is having fear based aggression caused by the attack.
No amount of physical corrections will make that fear go away.
If you let go of the idea that you have to use punishment to make the problem go away you will have a far easier time addressing the fear in your dog.
Rewards based training is not something just used for poodles in the circus. Most police, military, sport and competition dogs are trained with rewards, including food and toys. Corrections are kept to a minimum with many trainers.
Delilah needs to learn that she doesn't need to fear dogs, or what you may do to her when another dog is around.
If you can take a step back and except that there are other ways of training that have value, besides compulsion, you have a great chance of working through this with your dog and an experienced trainer.
When a dog saves the life of a man, it becomes clear that partnership knows no bounds.
Fama - T.E.D.D. OEF XI-XII (GSD)(RET)
Marshall - T.E.D.D. OEF XII-XIII (Lab)(SF EDD)
Lucian - Med Alert / Mobility SD (Cane Corso)
Pud - the old man (Pit x Lab)