Unfortunately I think that it's very possible that the Empress said this, is very well know that she was a very "possessive" wife, and sadly, she was the cause of many mistakes that Nicholas committed during his life.
I think that in that letter, Alexandra was trying to suggest to Nicholas to be more strong and determined, and I agree...but I wonder why she said "Be Peter the Great, Emperor Paul and so on...", I'm not agree with this at all!, what she wanted?, that her husband condemned to death all without compassion?...bad suggestion.
[/quote]
She indeed wrote that letter to his husband on December 14th 1916. In the same letter she says "Remember even M. Philippe said one dare not give constituion, as it would be Russia's ruin and all true Russians say the same... but my duty as wife and mother and Russia's mother obliges me to say all to you... blessed by our Friend...Be the Master, and all will bow down to you.. We have been placed by God on a throne and we must keep it firm and give it over to our son untouched..."
I doubt she literally meant to put to death to anybody "withouth compassion" but urged the Emperor to be firm. We couldn't call Alexandra a champion of politics, but it would be unfair to blame her for anything that happened to the Monarchy. Yes, she helped make the dynasty quite unpopular and her autocratic manners and Divine Rights nonense were completely out of place in a country that demanded civil rights more than ever, but she was only the Consort. If any responsability should be placed over one of them, it should be Nicholas. And being a firm Monarch wouldn't have been a bad idea after all.