Grrr
I used to do this when I was younger - think I only "deserved" male friends if they had the promise of sexual "reward".
Like I had to "protect their feelings" because my company alone wasn't good enough and I had to play along with whatever romantic fantasies they projected onto me.
Some very fucked up and draining interactions resulted from this mindset.
You need to spell it out to him clearly, and don't stint on telling him that you're OD (I mean I wouldn't give a blow by blow account, just as it's a bit boring for anyone!).
You slept with him. It was a one off. That doesn't entitle him to access to your vagina.
Even if you end up single/alone/childless you still don't have to have a relationship with any Nice Guy who feels entitled to your company and life.
I'd be very clear in setting a boundary ("It makes me uncomfortable when you talk about X as I don't feel that way") and if he drifts away, well you haven't lost much have you? What often strikes me about this kind of guy is they aren't embarassed about coming across as pushy/sleazy/creepy and forcing their attentions onto someone reluctant, yet they characterise themselves as victims done over by hard edged women!
Of course don't sleep with him again, that would be a bit much and twattish on your part 