I'm telling you, as a black man, the n-word would not be as bad as this. Trump's supporters are largely openly racist. There are few blacks amongst their number. Many of them, however, were women.
I don't think the problem for Trump would be losing the tiny handful of African American supporters he currently has, it would be that there is a portion of white voters who (in spite of everything else) have been saying to themselves "Well, Trump isn't really that racist is he?" who would have to reckon with the fact that, yes, he actually is that racist.
If they were bothered by the prospect of voting for a racist before now, they wouldn't still be considering voting for Trump. At this point, Trump is beyond dead girl live boy territory with 40% of the electorate.
sadly, more like at least 45%