Interesting piece. It's rare for any "white" person to admit/acknowledge that, yes, ALL so-called white people are racist. Black people understand this in ways that white people simply cannot -- and you hint at that a bit.
Your references to Marley K. are well placed. She is a, if not THE leader here on this matter. D'Angelo, as you admit, is not particularly insightful, though. She has done what all people who think they are white should do: She has read and absorbed people like Baldwin, Toni Morrison, Ralph Ellison, and many, many others, and simply distilled their ideas and works into a catchy, provocative term: "white fragility."
Unlike D'Angelo, though, you do acknowledge the toxicity of "racism." But you do not make the distinction between "racism" and white supremacy. As an anthropologist, you must know that "white" people invented "race" and racism. There's a long history of European "scholars," going all the way back through the Enlightenment to the Ancient Greeks, who first began dividing people up into "racial" categories and groups. See, Professor Emerita Nell Painter's 2010 book, "The History of White People."
Since Columbus first stumbled upon the Bahamas in 1492 and promptly enslaved and ultimately destroyed the entire Taino people, white supremacy has rampaged across the globe enslaving, exploiting, and destroying every single "native" population it has ever, EVER, encountered.
Another of my favorite authors is the late Susan Sontag, a Jew. In 1967, she wrote that, "The white race is a cancer upon the world." After coming under heavy criticism for this statement, she relented and apologized -- to cancer patients.
Again, an interesting read...and courageous.
(Oh...as for the comments by "Todd" above, there is little hope for so-called "white" people like him -- the majority, I'm afraid. He is in deep, deep denial, and cannot and will not understand that there is only one "problem" on this planet: white supremacy. As another author, Neely Fuller, has said: "If you don't understand white supremacy, then everything else will only confuse you").