Didn't Our Lord suffer fear, dread, anguish in the Garden? Or, no, did He just go frolicking into the Crucifixion...?
And didn't He say, "My God, my God, why have You forsaken me...?"
Those are the first words of a Messianic hymn, Psalm 22, unusual for the intensity of its feeling of having been abandoned by God Who is "far from my cry for help." The Psalm ends in a vision of future triumph; yet neither the Psalmist nor Jesus shies back from expressing the very depth of the temptation to despair, an abject sense of being deserted by God in one's hour of need.
If Mary felt these emotions, she did so right smack dab in the middle of the prophetic and messianic traditions of the Faith.
If you think the Pope was imputing sin to her, you are very much mistaken.
What I think is that when anyone (including a pope) slanders our Blessed Mother with a gratuitous, fictional tale, imputing thoughts to her which have absolutely ZERO basis in Sacred Scripture and characterizing her as undignified, whiney and disrespectful toward God, it is the duty of all true Catholics to come to her defense. Those Catholics who would defend insults toward our Blessed Mother are very much mistaken.
"O Jesus, it is for the love of You, in reparation for the offences committed against the Immaculate Heart of Mary, and for the conversion of poor sinners." - Sacrifice Prayer (Fatima)
It's more that that. Francis inferred the Blessed Mother may have despaired.