Is it normal to love your best friend?

Yes. I know the answer to that already. Sure, you can love your best friend. Obviously there's a reason to keep them around, you have so much in common, or you can't imagine your life without them... yadda yadda yadda.
Here's where my oh-crap-I-can't-believe-I-feel-this-way mentality comes from. (We'll call him Sam)
He loved me.
Well, that was until I broke his heart by 'dating' his best friend. But, because of all of that nonsense, the boy I may be in love with was able to hate me and (maybe) move on to thinking we could just be friends.
I thought that's what I wanted. I really did. But, things started to change a few months ago. My school was having a function and I was dating someone else. Now, this boy from my school, let's call him James, was a very different character. He was good looking and very charming. As far as first impressions go, I was smitten.
A few hours after what was our third date, I had ended up seeing Sam and a friend. Upon returning home from this mutual friend's house at around three AM, I realized that I had forgotten my keys to my house and was locked out.
I called Sam to keep me company over the phone while I checked my doors in the back of my house. It was nighttime and I'm seriously afraid of the dark. He knows this and stayed with me until I realized that everything was locked.
It couldn't have been more than a minute after my realization hit that he was at my house to help me try to get in.
Eventually I got in.
But, I didn't think to call anyone else. He was the only person I could think of to help me and he did. I don't know. Something clicked then. I needed him and I wasn't sure why anymore. While I was hugging him goodnight to thank him, well, it felt different. I wasn't so excited to let go.
So, here I've been, overanalyzing everything about him.
I don't have any right to ask him to try loving me again. I have no right to tell him that I love him. That isn't fair. I spent so much time convincing him that I'm not good for him or good at all.
But, when he did love me... he said he didn't have a reason and he liked it that way. It would ruin the magic.
I'm scared of the future. I want him so desperately in mine, but I know how these things work. When we eventually find other people, we're not going to be friends anymore. I doubt either significant other will condone five AM heart to hearts which occur on a regular basis. I also doubt that I could look at him the same way if he loved someone else more than he loved me.
That's petty. I know. Believe me, I know how ridiculous this is. But, I'm terrified. I can hardly say I love you to my parents. The fact that I'm considering being in love is mortifying. I've never felt more naked. And the worst part is, he can see right through me. So, lately, I've been avoiding him to keep everything to myself.
I hate that he isn't around right now.
I miss him.
I don't know what to do and I'm asking for any advice.

-A horrible best friend