In "Pride and Prejudice," why does Darcy turn white when he sees Wickham, and why does Wickham turn red?

I think maybe because Darcy wasn't expecting to see him with Elizabeth, and Wickham turned red maybe because he was embarrassed that Darcy showed up, and he's face to face with a man that he wronged and is worried about how Elizabeth would perceive it or notice it if Darcy were to say or do something that may make the truth come out.

It's been awhile since I've read it, so please forgive me lol! That's how I took it anyway. I hope that helps :)

Wickham turns red out of embarrasment and maybe even fear of being unmasked as the low life scum he is, and Darcy turns white out of indignation, and anger from seeing Wickham again after the ordeal he had made him go through with his sister.

It's because Darcy hates Wickham and he's like, why is he here? and Wickham KNOWS he acted bad towards Darcy and he doesn't want it to be like known.

If you've read the book how do you not know this?