Am I Overreacting?

I went over to my boyfriend's place after work and he and his friend were talking about something and giggling, and it took me a while to figure it out but it was about friend's wife and how she should go on OnlyFans cause she's hot, they make good money, and they'd be set for life.

I got a little pissed and called him out on it like why is this being discussed? He said they're just shooting shit and not serious about it and I was like well did you ask the girl? How come she's not a part of this conversation, it's about her. He said they're not serious and just talking about it but I was like, this is uncomfortable. It's not OK to be talking about best friends wife that way to your best friend! And the fact that they both didn't think it's wrong, is gross to me.

Long story short, I left because I didn't want to stay there. Then he said I wasn't being mature and to talk about it when I decided to grow up and be an adult.

I don't care if the woman is thinking about it or not, but that's between her and her man. Not him. He shouldn't have even entertained this kind of conversation. Even if it got brought up, then don't entertain it about someone else's girl. It's fine to notice and compliment someone while in a relationship but I felt like he crossed a line. Even if all three of them are fine with it, I'm not. I don't wanna be with someone who thinks that shit is OK. Am I overreacting?