Heidegger never separated from his wife, but he had a short affair with Hannah Arendt. Yes, that Hanna Arendt. Misbehaving Dasein? (Source.)
Despite distancing himself somewhat from Nazi politics, Heidegger was banned from teaching for a time after the war. Probably served him right. (Source.)
At one time, Heidegger thought about becoming a Roman Catholic priest. If this had come to pass, he might have written Being and Time and Eternity, which probably wouldn't have put him on the map. (Source.)
Poor health kept Heidegger away from both the seminary and the army. That's what gave him the time and space to write all that philosophy. (Source.)
While his involvement with Nazi politics (as Rector of the University of Freiburg) was short-lived, Heidegger apparently believed for a little while that he could move the Nazi cause in a better direction. Boy, did he have another thing coming. (Source).