I dunno if we're together or not, what's the best way to ask him?

me and this guy have been kinda "involved" for a while now..... but i dunno if it's "official", his best friend has been talking to me more and playfully accusing me of "stealing his best friend" but he's more than happy that we're KINDA together. so... we were talking and he was like "so is _____ your first boyfriend?" and i was like "ummmm..... he's not my bf???? not yet" so... i dunno if i completely just screwed it up, or if we're together now or not, the guy i'm involved with is in new york for the week so i cant talk to him till he gets back, so i dunno if i should ask his best friend.... because i'm uming he'd know. is that a good idea? or not? any other ideas?