Having second thoughts about my boyfriend?

I've been dating my boyfriend since 11.07.08 and we were friends for a while before that. I've always loved him. I moved to Colorado from Louisiana (my hometown) 01.11.09. and am going back down there 01.29.10. The problem is that....my best friend for two years, which is longer than I have known my boyfriend, has always been the one thing I could have that I wanted. Well...now she's with some guy who is allowing her to be...more or less friends with benefits with me, which I've never done before. It was her idea. I haven't told her my answer yet because I'm thinking about this really hard. I've been thinking of breaking up with him because I don't really feel like I'm into guys anymore. I'm pretty sure I'm a , and my friend's suggestion has made me come up with these thoughts. When I think of my boyfriend and I in a ual way, I get repulsed and I just can't talk to him. When I think that way about my friend and I...I'm okay with it. I still deeply love my boyfriend....what should I do about these second thoughts, because my boyfriend is planning on marrying me and he's talking kids and moving in together and the whole shebang. Please help. Thank you.