Mikamakamoo, I feel very sad for you. I went through exactly the same with my ex-husband and in the end we split up, which is probably not what you want to hear. I tried all the being understanding, being nice, trying to bring the subject up occasionally (once a year or so!) in a non-threatening way - to no avail.
We met when we were 21 and married when we were 27 - we were very close, best friends, and the sex was great at first, then gradually waned, as you might expect. However I never imagined that it would dwindle to nothing. The longest we went without sex was 2 years.
My experience was so like yours. I felt completely rejected as a woman, and although we snuggled on the sofa, kissed (no tongues!) and hugged, I started to become more and more resentful of him. He would cuddle me in bed but make sure his hands didn't touch any 'rude' bits! I know I was still his best friend and the mother of his children (managed to conceive them by making it clear to him when my fertile time was..) and I managed to kid myself that this would be enough.
It wasn't. As the marriage continued (we were married for 11 years and together for 18 in total) I got so frustrated and lonely, I pushed him away for not appreciating me as a woman, got more and more angry. We went to counselling twice many years apart (he was unfaithful to me before we had children) and he was unable to give any explanation for either his infidelity or later his lack of desire for me.
Finally I asked him to leave, cos I realised it would never get better. He finally pulled his finger out, went to the GP for tests (no physical reason of course), we even had sex a couple of times, but I was already having a secret affair and this had made me realise that I wanted and needed a proper relationship with friendship, love and sex. Also I was so angry that he had ignored my attempts to sort things out for so long and buried his head in the sand - I felt he obviously didn't value our marriage at all.
You are very brave to talk about this because it is so humiliating for oneself as a woman. After all, we're supposed to be the ones complaining about our ever-randy husbands bothering us for sex all the time aren't we? I wish I could give you some concrete advice, but all I can say is - the only thing that made my ex realise how serious the problem was for me was when I asked him to leave. Unfortunately by then I was totally disillusioned and had already detached myself from the relationship. Can you explain to him how destructive this situation is for your marriage and how deeply it affects your feelings for him?
Best wishes in sorting things out - I really hope you do!