Letters written by Jacqueline Kennedy to an Irish priest have revealed new details about her closely guarded private thoughts. The letters are set to be auctioned next month and could fetch up to $1.6 million.

The more than 30 letters were written to the Rev. Joseph Leonard. They were recently discovered in a drawer at All Hallows College.

In one, she questioned her faith after the assassination of President John F. Kennedy. "I am so bitter against God," she wrote a few months after the assassination of her husband.

In one letter sent over the span of 14 years, she writes about her early impressions of her future husband and how he was consumed by ambition.

Details about the letters were first reported by the Irish Times.