unburden oneself to

unburden (oneself) to (someone)

To share one's intimate emotions, thoughts, or secrets with someone else, especially that which is troubling, stressful, or distressing. I had simply asked him how things had been, when suddenly he unburdened himself to me about all the problems he's been dealing with in work. I apologize for unbosoming myself to you like that. I just haven't had anyone to talk to since the divorce.
See also: unburden
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

unburden oneself to someone

Fig. to tell someone about one's trouble or anxiety. I didn't mean to unburden myself to you. I'm just so upset. She unburdened herself to her mother.
See also: unburden
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
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References in classic literature ?
It's very seldom I talk as plainly as this to any, one but you are just the person one can unburden oneself to a little; and to tell you the truth, it's rather a relief.