How to deal with racism

I’m an Asian international student who is doing part time job in a big name company in Australia.

I had a colleague who usually seemed very helpful and nice. Before he resign, he said something racist in public. I was so shocked that I didn’t report it to HR immediately. It was nearly a month ago. Wondering if it’s too late to do something.

Let me recreate the scene: Me and 3 white boys were working together. They were talking about renting an apartment. I didn’t join the conversation. I was working around them. A coworker said he doesn’t want to live in a local suburb but didn’t say the reason. That coworker was about to resign said yeah lots of Asian people there. I was the only Asian on the spot and I was really uncomfortable hearing that. Also feel like he was public shaming on me. I also feel disappointed about the other two people. They didn’t say anything.

What should I do now? Kind sick of my job because of this.