Which preposition to use with unburden

of Occurrences 2%

[Thy sprite, I know, doth linger hereabout And looks that I, poor wretch, should after come; I would, God wot, my lord, if so I mought: But yet abide, I may perhaps devise Some way to be unburdened of my life, And with my ghost approach thee in some wise To do therein the duty of a wife.

in Occurrences 1%

It was to her that he unburdened in his letters the wild scheme of his marriage.

to Occurrences 1%

I sought Captain Haskell, and unburdened to him.

Which preposition to use with  unburden