CLEVELAND, Ohio -- A heart-wrenching letter penned 150 years ago by Mary Todd Lincoln to a Cleveland man named Charles Reeves is being auctioned online this month.

RR Auction of New Hampshire is estimating the sad narrative about the death of the first family's 11-year-old son, Willie, will sell for between $20,000 and $40,000.

"There are days when I feel I cannot struggle on much longer," Lincoln wrote in the letter dated May 5, 1862. "Please excuse this letter, written in much haste, and almost blotted by my tears."

"She's quite rare," said RR Auction Vice President Bobby Livingston, noting that a letter by the first lady to the War Department sold at a 2010 auction for $11,000....