Her life was marked by the same tragedy as that of her partner as she accompanied him into his final exile from Russia. Her son Leon Sedov was an active and leading member of the Bolshevik Leninist movement that his father led and was almost certainly assasinated as a result of that. Another son who was not politically active and remained in Russia was certainly murdered by agents of the man Trotsky called Stalin/Cain.
After her husband's assassination in 1940 Natalia Sedova remained in Mexico and maintained contact with many exiled revolutionaries. Her best known work in these last years was an autobiography of Trotsky which she co-authoered with fellow Russian revolutionary Victor Serge. She was also close to the Spainish revolutionary Graandizo Munis who had led the tiny Spanish Bolshevik Leninist Section during the revolutionary events in the 1930s. Under his influence she came to adopt a position that the USSR was a state capitalist society and that the Fourth International founded by Trotsky no longer held to the revolutionary program of Communism. Therefore she broke from the FI in disgust.