Little situation here, 😂 so any advice?...

Ok so I just started being fwb with an ex from middle school, and we barely saw each other like 3 times... Now 😂🙄 one of his friends text me if I wanted to go out to eat 😬 well nobody knows about our little situation, so I’m guessing the friend doesn’t know,

I never met him in person but has a lot of mutual friends,

but I think it would be weird on my part to say yes to going out to eat cause they’re friends, but he’s such a nice guy any advice? Should I ask the guy I’m fwb ??