"And until now no one has seemed to notice. "

This is not true. Almost everything you said in this article is correct, damning, and ugly. But it is not unknown, these things have been discussed for at least the last few decades. What is unique today is that previous similar periods have brought about "reforms", and many of us assumed that progress was being made. What the recent events have shown, combined with the increased exposure due to ubiquitous phone cams, is that any reforms that were made were minimal and have not made things better, in fact things seem worse. So everyone, including millions of White people, are now more motivated than ever to see real changes be made this time.

What I do object to is your title. Dear Black people, please quit saying "Dear White People". It is pedantic, it has been waay overused, and it implies that all White people are the same. Blacks get angry and insulted when White people complain, for example, that Blacks always vote the same in a bloc. They point out that Black people are not all the same. Neither are White people, and if you want us to stay motivated, I suggest you quit damning us and painting us all as racists.