Here's where we come to a cross roads.
1) him understanding he's poly is NOT the way to get him to understand YOU are poly. That is like saying for you to feel comfortable being a woman and comfortable with your sexuality as a woman, he needs to be a woman. If he doesn't want to try being poly, then getting him to understand it through practice is not an option.
2) "I'm just afraid of vaginas.. I wouldn't know what to do if faced with one" Then you aren't bi curious. If the idea of a woman's genitalia scares you, then you have your answer. It took me forever to realize that I wanted women not because society crams their beauty and erotic images of them selling EVERYTHING down my throat but because I physically wanted every part of them as well. I've seen a woman who was bi curious before. Seeing a woman who says she's exploring but afraid of vaginas? Out of the question.
Certainly you can find ways to justify things in your own mind, and that's fine for you. However, people here are trying to help and let you see how things look outside of that justification. Trying to get your partner to understand what you want by living what you want won't work. To be perfectly frank, he doesn't NEED to understand. Trust me, after 20 years there are things hubby and I just DON"T understand about each other. But we accept them. That's what's important.
Me: Late 30s pansexual poly.
DH: My husband of 19 yrs and father of 3 teen girls.
DC: LDR of +4 year