I'm a non-white living in America who HAS experienced racism, and who has seen black friends who have experienced much worse racism. That being said... I have many black friends who are exceptionally successful and many white friends who are wonderful, non-racist people.
I think racism does exist because there will always be people with hatred or fear in their hearts. But I think most of us are trying to do better. And that is all any of us can do as human beings.
I am glad that you are sharing honestly your experiences. Even if my experiences are different, it is good to learn what others have gone through. We can learn from each other.