Can't have him back

I thought this guy was cute, and one of my friends told me that he thought I was cute too. We started talking a little bit and my friend told me that he is starting to like me. Before we met he really, really, really liked another girl, but she didn't like him back like that, and me and that girl are friends.

But then we would see each other everywhere and he started liking me, but he still kinda had feelings for her. So I tell my friend who told me about him that I wanna be friends if he doesn't fully like me. So she told him that (I wanted her to) and he went back to liking the other girl who didn't like him back. I feel as if I made that biggest mistake of my life when I said I wanted to be friends. I don't know what to do and in my religion, it is bad to date so I'm not gonna tell him that I like him, up front. I don't know what to do and I want him to like me again.