We Need to Talk About Kevin, by Lionel Shriver, 400 pages
This was an absolutely brilliant work of fiction. The subject matter is uncomfortable, the characters are all pretty reprehensible, but it is so totally honest and raw- it was kind of like reading a work of horror fiction. Eva is writing letters explaining how her son, Kevin, committed a school-mass-murder, and events leading up to it. It's a fascinating look into reluctant motherhood, among many other topics. This was recommended as one of John Waters' favorite books, and as usual, he was right.