What should I do if I love my best friend?

GO FOR IT!
he knows you beater than anyone.
if you love him then:
A) tell him how you feel!
B)don't go to over the top telling him just say something like"i want to tell you something, I love you" something to that effect.
if he's your best friend then I think that would make it a lot smoother in a relationship.

Just tell him. it could turn out to be a good thing.you never know unless you try.

I thought that I was in love with my best friend too, and when I told him he said "Well I don't feel that way I feel like your a sister to me, and if you feel like that then I don't want to hang out anymore because I can't keep hurting you" and I really respected that. Adn I also thought to myself. wow I would rather live with him being my best friend then to not have him in my life at all. So as hard as it was I forgot all the feelings I had for him and to this day he is and always will be my very best friend. I love him so much, but in a friend kind of way. I watched him get married and have a beautiful daughter who now calls me her aunt. I coulnd;t be happier with the way things turned out.

Hope I helped a little bit. good luck