When I was a child my father was in charge of a mental aftercare home. This was a place for people who had spent long periods of time in an asylum. There was a woman there named Maria, she had numbers tattooed on her arm because as a little girl she was a prisoner in Auschwitz. She ended up in a British asylum because she witnessed her entire families murder, her Mother, Father, Grandparents and baby brother.
So yes, I think there's a pretty good chance the Holocaust was real.