There are exactly two books (well, one of them is three parts) that literally put me in a terrible funk for days and days after reading them. One is Solzhenitsyn's Gulag Archipelago, and the other is Martin Gilbert's The Holocaust. Knowing those stories intellectually is one thing; knowing them at that kind of detail is something else.
If you learn the history of this country, you learn both to be vigilant and push back, and to have some confidence that it is a passing era. This is not the first time; look at the Civil War, particularly in places like Missouri and Kentucky. Look at Eugene Debs in WWI; look at McCarthy. It passes. In part it passes because of those who are forever bitching about it, even tho they sometimes feel like, and are treated like, Chicklen Littles.
My favorite line in this regard was a quote from Jean-Francois Revel, the author of How Democracies Perish. He used to tell a story about his European friends were forever bemoaning the dark night of Fascism falling in America (this is over the course of the last fifty years or so). Revel observed that he found it curious that while the "dark night of Fascism" was forever falling in America, that it seemed to only touch ground in Europe.
Best. Geo