To my knowledge Hitler didn´t kill anyone. Stalin killing Lenin? Never heard. However his son was captured by the Germans in 1941. The Germans proposed to exchange him with one random German captive. However Stalin, who had troubles with his son (I can understand his son...), declined as saying it was duty to die and not being captured. IIRC his son commited suicide in 1943. IMO Stalin is responsible for his death and I can´t explain, why a father is able to do that. But hey, it was Stalin. So it is no wonder that he wife became ill.