Shy,
I agree with the others - cheating on your husband isn't going to make things any better.
I've recommended this book many times in the past. There are two good things about it. First is that it explains how to approach a "confrontation" in a non-confrontational way.
But it also has one of the best passages in any relationship book - specifically about sexual fantasies.
http://www.amazon.co.uk/Seven-Principles-Making-Marriage-Work/dp/0752837265
You can pick up a used copy for under two quid.
"Your sexual life will be further enhanced if you feel safe enough
to share your sexual fantasies with each other and even act them out
together. This is a very delicate area. Although fantasies are the home
of imagination, variety, and adventure in a marriage, very few
couples are able to share their fantasies and then find some way of
honoring them within their sex life. If you are able to share your
fantasies, the result will be great intimacy, romance, and excitement.
Try to cultivate the idea that within the boundaries of your
marriage, all wishes, images, fantasies, and desires are acceptable.
Nothing is intrinsically bad or disgusting. You can say no to your
partner's request, but don't disparage it. Expressing a fantasy
requires a great deal of trust, so take care to be tender when you hear
of a fantasy your partner has. If it's not one of your own, but it's not a
turn-off, then agree to it. Don't take it personally if your spouse
wants you to pretend to be a stranger, a nurse, or a pirate. Just
consider it play The idea, the desire, the fantasy is usually not
understood at all by the person expressing it. No one knows why
particular fantasies are erotic to certain people, they just are."
You made an interesting statement..."he finks I need help!"
People - and particularly men - have difficulty expressing vulnerability, and they often react in a mocking way when their ideas are challenged.
I hate to mention this book here, but if there's one thing that 50 Shades of Grey had shown is that there seems to be a reservoir of unexpressed sexual fantasies in the general population.
Perhaps you do "need help" - but it's not because you're being unreasonable or because you're crazy. It's just because you have a relationship that's in trouble.
You absolutely need to talk to him about your feelings, and if that's not possible between the two of you, then an experienced couples counsellor can be a good way to prevent things getting out of hand.
The worst thing you can do is not take any action, and just to go on being unhappy.
Cheers,
Stanley