In light of the recent, racially-charged events in the U.S. involving the police, Serena Williams is speaking out – and she's not mincing words. 

In a Facebook post on Tuesday, the youngest Williams sister shared a story about how she was afraid for her nephew's life when she was riding with him. She started by saying her nephew, who is 18, was driving her so she could do work on her phone.

"In the distance I saw cop on the side of the road. I quickly checked to see if he was obliging by the speed limit. Than I remembered that horrible video of the woman in the car when a cop shot her boyfriend. All of this went through my mind in a matter of seconds. I even regretted not driving myself. I would never forgive myself if something happened to my nephew. He's so innocent. So were all 'the others.'" 

Williams was referring to Philando Castile, whose death was shot by his girlfriend Diamond Reynolds, as well as all the other victims of police brutality the past few months.She gets deep about the barriers we have faced since the dawn of American history, and long we still have to go.

"Why did I have to think about this in 2016? Have we not gone through enough, opened so many doors, impacted billions of lives? But I realized we must stride on – for it's not how far we have come but how much further still we have to go." 

Serena ponders if she has done what she can to bring attention to the issue, but notes that she won't keep quiet.

"I than wondered than have I spoken up? I had to take a look at me. What about my nephews? What if I have a son and what about my daughters? As Dr. Martin Luther King said " There comes a time when silence is betrayal." 

The tennis legend ended the the post by saying she "won't be silent."