I have had times in my married life when I did not want sex with my husband. For me, it wasn't at any particular age, but when I was mourning my parents and later my sister.
We got through the rough patches because DH and I could discuss the matter frankly without my making him feel he was a rapist, and without him making me feel I was frigid.
It sounds to me, as if you cannot discuss this frankly with your husband or find a way of making him understand that you need to be free to say no for a while.
How you solve the problem in the long term, I cannot tell you, I doubt anyone can.
I agree with those who say that your husband has no right to force himself upon you, but equally I do not think a wife has the right to deny her husband intimacy for ever.
So you need to decide, what is important? Staying together at all costs, even if it means you "allowing" your husband to find some other woman who will have sex with him? Or would divorce be the only solution? Can the pair of you find other ways of demonstrating that you love each other, if you still do?
Your husband forcing you to have sex, or you forcing him to abstain for the thirty or more years you both reasonably can hope to live is just not on, is it?
And before the rampant Women's Libbers start shouting that no man has the right to force anyone to have sex: I agree BUT both men and women marry on the understanding that sex is part of marriage. If by mutual consent it is not, or is not any longer then there is no problem, but as long as one party wants it, and the other does not, there is a gigantic elephant in the bedroom.