DO NOT release this tadpole. This is exactly how introduced species occur and how disease gets spread. Chances are this tadpole came from southern USA. The species may be native but the genes are not. Ironically, bent tails and misshappened bodies are often associated with disease and parasites in tadpoles. I reccommend quarantining this animal away from the rest of your collection. If you are not prepared to take care of a large Bullfrog for the rest of its life, you should consider euthanizing it now. Unfortunate, yes. But releasing this animal would be extremely irresponsible and may actually be illegal in your state.