Slightly tangential, but Hannah Arendt, in addition to being a political philosopher, wrote a fairly thought-provoking tome called 'The Origins of Totalitarianism'. Worth a read if one is interested in such things.

https://en.wikipedia.org/wiki/The_Origins_of_Totalitarianism

I'm not completely well-versed in Heidegger, but is it possible that he did not hold his Nazi beliefs so close to his heart that true love (corny, I know) could not usurp those feelings? I would not suggest that a man such as Heidegger would not be forthcoming in his beliefs, but I do think it's possible that him (and others throughout history) adopted political beliefs partially out of convenience. Sometimes, it's difficult to tell the lengths to which someone holds their convictions.

Yeah I’ve read about half of origins of totalitarianism. Really unique book. One interesting thing I read is how she shows that colonialism from the dominating powers was quite often rooted in capitalist goals. And so she shows how underpinning totalitarianism and powers spreading over other countries was the result of greed by those in power. Makes sense, but I never think of how capitalism could lead to that.

Although not a technical book, 'At the Existentialist Cafe' goes quite deeply into Heidegger's relationship with Arendt and Husserl and his time as a member of the Nazi party. It's quite damning if it's true.

https://en.wikipedia.org/wiki/At_the_Existentialist_Cafe

Even weirder, before their love letters were published, Richard Rorty wrote a kind of hypothetical apology for Heidegger where he says "Well, if his life had been different and his lover were Jewish, maybe he could have had the same philosophy but not been a literal Nazi"—except he totally did have a Jewish lover and a Jewish mentor professor and still, Nazi.

Arendt actually met Heidegger prior to the rise of the Nazi party. That said, Arendt continued corresponding with Heidegger long after he officially joined the Nazi party. It was definitely a weird, problematic relationship.

What's worse imo is Heidegger's treatment of Edmund Husserl. I don't think it would be a stretch to say Heidegger threw Husserl under a bus when the Nazis came to power.

Arendt later recalled Heidegger as someone who "fell into his own trap." AFAIK, Heidegger was not an ardent Nazi, who joined the party anyways for practical purposes. As Sarah Bakewell, author of "At the Existentialist Cafe",[1] would characterize him as "lacking personality." He wanted to reform education, but failed to gain enough political influence within the party to do so. Even after WW2, he never issued an official comment on his affiliation with Nazism.

[1] Recommended read. Touches on interactions among existentialist thinkers like Karl Jaspers, Maurice Merleau-Ponty, Jean-Paul Sarte, Edmund Hurssel.