I don't think anything is wrong with you. You are clearly a lovely woman and from what you wrote, are also introspective and intelligent. That said, I am not sure how to advise you. My first thought was that perhaps you have not yet met the right black man. I think it is a shame that all of the ones you have been involved with left you with a bad overall impression.
Best thing I can think to tell you is to open your mind back up and give equal opportunity to any man you meet, regardless of his ethnicity. Don't turn your back on an entire race of men. Perhaps you will date and fall in love with a white man, as long as both of you are prepared for, and have the strength to deal with, the negativity that relationship will engender in your country - then you should also stay open to white men (or Latino men etc etc).
Absolutely do listen to your heart - as long as your brain has told your heart to be open to all men. Those are my thoughts anyway. I hope you find someone with whom you find love, happiness and fulfillment. :) Roxy