I find I can relate to a lot of what you say if we just jettisoned the word "punishment." The two punishment spankings I had in my life didn't do ANY of this for me. One did help me release some of my feelings. It was not against my will. I asked for it.
Part of what you are feeling, please realize, is also the effect of the endorphins released by the spanking. They are a powerful drug indeed.