When your husband tells you he is not attracted to men he is most likely telling the truth. That doesn't necessarily mean he is straight in the conventional sense. There is a phenomenon common among crossdressers that has been called psuedo-bisexuality. True bisexuals are attracted to both men and/or women. Psuedo-bisexual males are attracted to women and also to the idea of being a woman (or sometimes a gay bottom) sexually. The males or male parts in these fantasies are just placeholders that allow them to be a woman (or a fairy). Some will even have sex with men but are not attracted to them in any sense other than as sex objects used to actualize their own "femininity."
Don't make the mistake of thinking that the denizens of this forum are representative of typical crossdressers. This forum tends to attract those CDs with gender identity issues while for the vast majority of CDs it's a minor sexual kink - nothing they would bother joining a forum for. From your description, your husband sounds like a typical CD and I wouldn't assume there is more to it than that without more evidence. For some, like myself, it's a major sexual kink that is more like a sexual orientation and prevents one from having a "normal" sex life. I joined forums like this because I was ashamed of and baffled by my fetish and wanted to believe there was more to it, that there was some inner woman that was trying to express herself and that my strange sexual proclivities were the result of trying to repress her. But that was a delusion. Sometimes a fetish is just a fetish. It turns out that my gender identity issues were the result of attempts to sublimate my fetish.
This can work in a marriage. I've been married for nearly 23 years and we had a very active sex life until she reached menopause. Before that she had a much higher sex drive than I did. Now it's about the same. Although I crossdressed when I was younger, I didn't return to crossdressing until about four years into our marriage. I never hid it from her. I just announced one day that I wanted to try it. She was good with it. I don't think my CDing does anything for her but she likes it because it turns me on. Our sex life worked even before that because she likes being the top and I like being a bottom. For me female domination has always been my primary sexual orientation where feminization and other emasculating activities are adjunct. Where there is a will there is a way. Where there is no will there is always divorce.