It seems another instance of police brutality against a black man surfaces every week, and Serena Williams is no longer staying silent. She got super candid in a recent Facebook post, talking about the panic she felt after seeing a cop car in the distance while driving with her nephew.

She instantly thought of the Facebook live video that went viral in July of a woman sitting in the passenger seat next to her boyfriend who had just been shot and killed by the police. Could something similar happen to Williams? The sad reality is it could. Hopefully by sharing her story (check out the full text below), the all-star tennis player can help others better understand the worries black people have to deal with every day:

Today I asked my 18 year old nephew (to be clear he’s black) to drive me to my meetings, so I can [sic] work on my phone #safteyfirst. In the distance I saw [a] cop on the side of the road. I quickly checked to see if [my nephew] was obliging by the speed limit. Then 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.”

I am a total believer that not “everyone” is bad. It is just the ones that are ignorant, afraid, uneducated, and insensitive that is affecting millions and millions of lives.

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…

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.”