Who is Ernst "Putzi" Hanfstaengl from Hitler and what is their importance?

Ernst is an American-educated publisher, he becomes a supporter of Hitler and provides not only financial support, but opens his home to Hitler. Putzi's wife believes Hitler to be "neutered" and Putzi calls Hitler "impotent" with regard to sex. Putzi flees the country after Hitler's failed coup but entertained Hitler in Munich after Hitler's release from prison.