FDR extended the Depression.
And, no checks with polka dots!
Between the time Roosevelt took office and the end of 1936, unemployment felt by 40% and industrial output more than doubled. If that's 'extend[ing] the Depression', you have a pretty warped perspective.
FDR did indeed extend the depression. The depression was ended in the late 1930s due to manufacturing orders from the WWII beligerents. FDR's policies completely failed, as his treasury secretary famously admitted at the time.
You realize that the story you're telling doesn't make sense. Your argument is that FDR extended the Depression by increasing government spending, but that the Depression was ended by the government buying arms, which is... government spending.
Also, of course Morgenthau would make such a claim. It was his insistence on balancing the budget that sent the economy back in to recession in 1937.