Besides the regular anti-white baggage she brought with her into the white house, the Tea Party and birtherism (and Trump being one of the biggest critics of her husband via birtherism) caused Michelle to believe all white people are evil/beyond redemption.
Michelle truly came to believe that the Tea Party's racist elements PLUS Birtherism was proof that all white people were beyond salvation/are the devil and proof that her existing hatred for white people was fully justified. And the fact that Trump fucking got elected as a huge "fuck you" bitchslap to her and her husband, given what a high profile thorn in their side Trump was, was just the icing on the cake towards triggering her to the degree that she hates white people enough not to trust herself screeching anti-white "kill the white devil" hate speech if she had to run for public office, as far as how much she DESPISES white America.