"I know he doesn't technically have a 'right' to sex"
Technically nothing, he doesn't have a right to have sex with you, end of. This is not Afghanistan!
"but I do think it's an important part of a good relationship"
It is, as long as it is given freely and lovingly (or lustily)...
"and that if he doesn't get any I"m storing up probs for the long term"
...and this is where I get concerned. Sex is all about him in this sentence. Never mind your needs to not be his sex kitten when pregnant, perfectly reasonable in the circumstances. Sex appears to be about his sexual needs alone, and that is not healthy.
Sex is not a service you provide for your partner like doing the laundry FFS, it is a gift you share with them. I wouldn't give anyone a gift that made me angry. I wouldn't give anyone a gift if it weren't given freely.
I strongly feel that if the touch of someone, husband or nay, makes you feel violently angry then you should not be having sex with them! It is a strong message from your body and psyche that it doesn't like what is happening. I think that ignoring clear messages like that will store up far more problems for the future than taking a break from sex because pregnancy is turning you off.
I'm well aware that there's a lot of women on MN who think that lying back and thinking of England (or Twilight) is sometimes necessary for a good marriage. I strongly disagree. It's just so dishonest, never a good thing for sexual partners.