Well, my parents wouldn't give details about their sex lives, but we were WELL aware that they had a healthy one. Kind of hard to hide that stuff in a 900 square foot apartment, especially from teenagers.
There would be jokes about their sex life when we were older (I once pointed out an grossly fat woman --she had to weigh about 450 lbs -- and nudged my mom and asked her if we should approach her on behalf of my dad, as a mistress [okay--before people get REALLY weird, it's an ongoing family joke. We ALL send pictures of toothless, hairy, fat, ugly AWFUL looking people as possible mates for each other, even the married people] and she gave a look and said "No, you dad likes me on top sometimes and she'd squish him". Ew.) but my parents NEVER told us details.
The long and short of it is that we were taught to respect our bodies,and to make anyone we were dating respect our bodies, but that sex is something that can and should be talked about. If you had talked to your boyfriend about your views before you talked to your parents about his fantasies, you wouldn't be where you are right now. You were in a 5 month relationship and had sex with him before you could TALK about sex with him? How silly is that?
All of that being said--tell him you're sorry, it's over and ask him please not to contact you any more. You can not salvage this relationship at this point--you think he's perverted, you told his fantasies to your parents (which I agree he has the right to be upset about). I don't blame him, either, for being upset that you're ending the relationship over a problem he didn't even know existed until you ended things--how is THAT communication in a relationship, anyway? You're supposted to talk to EACH OTHER, not friends and parents!--but the fact is, the actions by both of you have doomed this relationship at this point.
