Re: Just sayin'....
You are 100% correct that Russia would have been destroyed without lend-lease but with lend-lease the Russian would have beaten Germany with or without a D day.
The only thing that D day accomplished was to prevent the Russians from overrunning Europe more than they did.
This is not to say Russia would have won without the U.S. and Brits. Air power severely hampered the Germans ability to wage a crushing air war against the Russians.