You infer that talking about and analysing your sexual relationship will take away its mystique and spontanaeity and I see that attitude as part of the same problem. It sounds as though you and your husband never talk about sex at all - it just happens and nothing is mentioned before, during or afterwards.
It could be that you are both treating sex as something that is too sacred and mysterious even to discuss, when a better approach might be to take it down a peg or two and give it parity with other aspects of marriage and family i.e. child-raising, finances, careers, houses. Talking about sex as a couple tends to promote libido, but you perhaps both need to get over your discomfort and the reverance you accord to sex.
It does sound as though the sexual side of yourself has always been a part that you felt embarrassed to acknowledge and embrace. I genuinely think some therapy could help with that and might be able to unlock when and why this first started.
Do you masturbate? This is something that will help you to find what sensations your body responds to and will also allow you to become comfortable with your own nudity and the pleasure your body can give you.
Again, please note that the primary objective in this is that you find what makes you tick as a sexual being. It's a gift you are giving to yourself and shouldn't be done in order to prevent your husband straying (because you can't do that - only he can). Once you learn to embrace your sexuality and take comfort in the delight and pleasure it can give you, the effects that will have elsewhere in your life will be delicious bonuses; an open and enjoyable sex life with your husband, greater intimacy in your relationship and crucially, better parenting because I presume you don't want your children to grow up feeling ashamed and embarrassed about sex?
You see, while it's helpful to see sex as a positive thing and not something mysterious and sacred, it is an aspect of ourselves that has the power to impact on so many other sources of happiness and wellbeing. Because of that, it's something well worth investing in and giving the same (if not more) attention to than all the other 'bits' of life, like parenting, friendship within and external to marriage, careers, money, houses.