I have a crush on my father in law

I’ve had this up and down crush ever since I met him when I first was dating my boyfriend at 15, now I’m 19. Some times the crush goes away but it always always comes back. My boyfriend and my father in law aren’t related. He is a step father to my boyfriend. I’m not married. But it’s easier to call him my father in law. In my eyes he’s so attractive, sometimes I think he’s giving me a hint he likes me and other times I’m so sure he only thinks of me as a friend. I’m tempted to just tell him but I have no idea how. His hugs give me butterflies. When I caught him staring at me, my heart sank into my chest, like could he actually be checking me out? Then right after he catches me staring at me and I quickly look away. As if nothing happened. He’s married he has a wife, no kids. When we are around I feel like I can feel the presence of his eyes watching me which I enjoy but I never look to actually find out because I’m a wuss. I want nothing more but to tell him and engage in the unspeakable. How dirty, disgusting, and wrong of me. But I love it.