I’d say maybe excuse it this one time because he didn’t know how you felt about him going to a strip club. Be very honest with him and depending on his reaction and also if he does this again, knowing how you feel, let him go

You’re sexually invested, its cheating babe. You say you dont care if he gets flustered or whatever but its not the same as you engaging in conversations like that with another person. Maybe you havent cheated but you’re on your way to that. I say either tell him or cut contact and block that person out of respect to your bf