HH,
I'm almost lost for words. With regard to this though: "The memory of this shames me - more than 60 years later", I can only suggest that the 13-year-old you was almost certainly a very different person to the 15-year-old you, let alone to the adult you. That is, the "me" that feels shame now wasn't the "me" you were when you were 13. To a significant extent you're ashamed of someone else, not of yourself.