I think that the stituation speaks volumes about how comfortable he is with you, I don't think you should blow that by being too harsh, but I'd definatly refer him to your boyfriend if:

A: He has more questions.
B: You aren't comfortable with answering them.
C: Your boyfriend is ok with that.

If he persists, then I'll give my usual advice - be hounest with him, tell him you arent comfortable with discussing such things, and refer him to the internet (but not LPSG for the sake of not letting him read your thoughts which presumably you are posting here because you don't want people close to you in Real Life to read), or your boyfriend, and refuse to discuss anything like that again.