The Jungle by Upton Sinclair. The book was intended to be a pitch for socialism but the American audience at the time totally missed that and focused on the horrible conditions of the meat packing industry presented in the story. Conditions that were described pretty accurately.

I don’t have a specific worst. The best was when I was complaining about my [then] wife for the umpteenth time. I don’t remember which sub it was. Someone responded with, “Are you familiar with Borderline Personality Disorder? If not, you should look it up.”

I did look it up. It explained everything I had seen up to that point. It is as like someone had written a text book about my wife. I was both relieved and terrified.

That was the starting point of getting out of that awful abusive relationship and getting my life back on track.