What an honest and courageous inquiry, C.. You might be looking at an important choice to make if you intend to stay married.
Here's are a couple of questions you might consider: If you learned your husband had a similar attraction to another woman, how would you feel? Would you be upset that he's spending his emotional energy on somebody else? Even if he assured you it was "just" a crush, would you feel threatened or alarmed that he might eventually choose the other person over you?
There's a lot of information in an honest answer, because we generally "project" onto others the feelings, motives and needs that exist in ourselves. In other words, if you'd be afraid he might leave you, you have found within yourself the potential for leaving him.
It's possible to have good friends of any gender, and even acknowledge a little buzz of sexual tension, without your feelings for your friends becoming a distraction from your primary commitment. And It's great to have friendships that are stimulating or nourishing, no matter the gender of your friends.
But there is a difference between a friendship and a crush, which we feel when we imagine the desired one might fulfill needs that are not quite conscious in us.
I'm assuming preserving/deepening your marriage is important to you. Since "crushes" are a repeating event for you, you might want to consider counseling. Sometimes relationships or events in our childhoods set us up for needing a little self-destructive chaos in our adult relationships. A counselor might be able to help you recognize underlying patterns, learn what your underlying needs are, and find ways to meet these within your marriage.