Fuck buddy?

i'm 18, a girl and at college, is it normal that i'm "just fucking" one of my best guy-friends?. plus this "friend" kind of disgusts me, he's quite good-looking, but not my type, and i only get with him because it's easier than not getting with him, (he's more in to me than me to him) and because i get turned on by how much he wants me. yes i know i'm being a bit of a bitch, but is it fairly normal behaviour?