Oh, Andrea, how hard this must be. Thank goodness, though, that he wasn't four--and will get new teeth!
Consider treating it like a naturally falling out--since most kids are five or six when their teeth start falling out to be replaced by adult teeth, he's just "ahead" of them... My son's in the opposite group, for he's one of only three in his kindergarten class who has not lost a tooth.
If you are cheery about it, and make up fun stuff to say about it, that will make it easier for your child. He may be less self-conscious than you think, and asking him questions about it and treating it like it's cool (rather than scary) can help him look forward to getting his big teeth some day.
Good luck!