Virgins on a wedding night are rare, indeed! I was one. Many people had some good advice for you, but there's something I don't agree with. Just because your fiancé has had sex, doesn't make him an experienced lover. The bottom line is that he's not yet had sex with YOU...therefore, he is inexperienced. Every woman is different.
Your fear is most likely rooted in 1) the unknown...the "big mystery;" and 2) ignorance (I don't mean this in a bad or critical way. I'll explain what I mean.)
The "unknown" will remain that way until you've joined with your husband. But even after that first time, it will *still* be mysterious because you'll both have SO MUCH to learn about each other and about yourselves. What you like, what you dislike, what really gets you going, what makes you giggle, etc. Have fun learning all that stuff! You're in this together. Communicate with each other. :)
Ignorance - Maybe you're scared in part because you have no idea what to expect. Maybe you don't know your own body yet. This isn't something to be ashamed of; it's just a matter of fact. The remedy for this is education. You and your fiance should read about and discuss together what to expect. How a man's body works, how a woman's body works, etc. Talk with each other about your fears, expectations, desires. And honey, do yourself a favor. Examine your body. Use a mirror if you have to, but get comfortable with yourself. The more comfortable you are with yourself, and the more you understand about you and your husband, the more confident you'll be that first time around and the more fun you'll have exploring! ; )
Now everybody told me I'd feel pain the first time. I didn't. Not a bit. That was partly because I had umm...can I say this on here? Well, I had an accident as a child that did away with "the veil that causes pain." You know what I mean. But sex can still be painful if you are not properly prepared...i.e. turned on. This is where reading a book on the subject can help you. Understanding precisely how your body functions internally and externally goes a long way to dispelling some of the mystery and fear. And if you're properly "prepared," it's not going to hurt.
So, read together, talk together, talk to close trusted friends, and then finally relax and give each other the freedom to explore and learn. Wishing you joy and much love. : )