It is said that FDR would have abandoned England to save Uncle Joe and his soviet friends
Who said that?
As low of an opinion as I have of FDR, I don't think that assertion even makes sense considering the fact that the USSR was on Germany's side until June 1941 (when Hitler backstabbed the USSR in Operation Barbarossa), but FDR was already providing the Brits considerable aid in advance of then. Official Lend-lease was passed in March 1941, and we were helping well before that.
Looking at Chapter 21, "We Are No Longer Alone", of Martin Gilbert's magisterial Churchill and America, which covers the period from January 1941 to April 1941, it's abundantly clear that FDR was 100% for the Allies in their darkest hours when Stalin and Hitler were still working together under the 1939 Molotov–Ribbentrop Pact.