I'm almost 40 and a newlywed. I was a virgin! Unfortunately, sex has not been good for me. His heart races, he sweats. Me? Nothing. No pleasure, no excitement, nothing! I WANT SOME TOO!!! I tried talking to him and we have tried several positions, unfortunately, his favorite missionary position usually hurts. I tend to just give in and pretend I'm enjoying it. I'm hoping you can help or at least lead me to someone who can!
I see several different issues here, at least, starting with: Why were you still a virgin at 40? This is rare enough to merit mention, especially under the circumstances.
2) Does he have a lot of experience to your none, or were you both late bloomers?
3) Pain with missionary position? No good, and not normal.
4) Faking it. A classic example of "seems like a good idea at the time." Isn't.
OK, so. I'm going to assume that there was something unappealing about either sex, intimacy, or both, for you to leave it so long. There is nothing inherently wrong with not having sex, but it's a better fit for those who simply aren't interested. You manifestly are interested, so that is something to look at.
I'd really like to know if he is having fun while you're not. It's kind of hilariously awful to think of you both having ungratifying sex night after night and nobody ever mentioning it, but I'm thinking that's not what's going on. He is having OK sex while you are not. Also awful, less funny, and a little harder to broach, what with your having to burst his bubble, but burst it you must. Bring it up as a mutual thing, let's make it better all around, and so on. But you are going to have to admit that you are not, shall we say, fully engaged. Not talking about it about it is guaranteed to eventually break everything not yet broken. I wouldn't rule out some counseling with a sex-positive counselor, either.
Finally, you are going to have to figure out what you do want if this is ever to improve. If you masturbate, you fantasize. How can you get real life better aligned with fantasy life? If you're thinking it would be nice if he started slower, paid more attention to your clitoris, and made sure you were responding before he kept doing something, we've got something to work with.
As far as how-tos go, I doubt you need a tutorial in hip-moving. But if you do, there is a world of instructional material out there. It is called porn. If that sounds icky, you can try the amateur stuff or any of the seemingly dozens of series with names like "Better Sex" or "Loving Couples." Bonus: watching any of these things together is going to at least start you on the way to the sweating and elevated heart-rate you so justly deserve to experience.
I think your libido is fine. You're not getting excited because who gets excited anticipating something dull and a little painful? Get that looked at.