And yes, the bourgeois parties hated the Marxist-Leninists much more than the Nazis who they collaborated with.
You say "the bourgeois parties," but that's all the parties besides the KPD. That's more than 80% of German voters in 1932. After the depression, the war, the austerity, more people still voted for the SPD, and all the other parties, than the KPD. Those voters couldn't all be members of the capitalist class. In fact, I'm pretty darn certain they were mostly working class people.