White bf + N word

I’m dating a guy who’s white and I’m black. I was over at his house and while he was singing a song he said the n word. I think he realized that I might’ve been listening because he kinda mumbled the other words to make it sound like it wasn’t the n word 😬. I pretended not to hear it.

It’s pretty new. We’ve been together a little over a month.

Idk how I should have reacted in that situation 😳. Anyone have similar stories about this kind of situation??