What you described reminded me so much of myself! I will never stop having those loving feelings for boys. It can't be wrong to love them!
As for the sexual feelings, they won't stop either. As Heather said, this is not a uniquely BL problem. I'm sure straight men notice beautiful women at church all the time. I still don't always know what the difference is between appreciating beauty and lusting. I guess when I see a gorgeous boy I try to imagine loving and knowing him as a person, rather than using him to satisfy my sexual desires. But the idea of being sexual with him in the context of a caring relationship and when he is ready is appealing to me. Is it wrong for me to fantasize about that? Like you, I have never been sexual with a boy.
I am sure it is possible to say no to a boy regarding sex with sensitivity so as not to make him feel rejected. In fact, we do it regarding many other things. I too think that if I ever had sex with a boy, I would always fear being found out, and more importantly, fear that he would later be (or at least feel) harmed by it. It's possible that because of my fears I would be even less ready for sex than he would be!
Heather's advice about a pastoral counselor sounds good to me; I'd love to find an understanding one, but they are probably rare and I haven't taken the risk to seek one out.
I hope this helps a little, and that you'll come here often!