my BEST friend and my best FRIEND

I have my BEST friend and my best FRIEND, both of them are also friends. These best FRIEND of mine is so cool, smart, friendly, so kind, so religious, a warm hearted person and is in love with my BEST friend. My BEST friend is one of the "best and true" friend I've ever met. A very charming, kind, jolly, simple,caring and loving friend. Three of us are always sharing thoughts, ideas, solutions in every problems and always having fun during spare times. Before, I thought that our friendship will have no room for those feelings that are more than friends but as the time goes so fast and those feelings were not be able to control. My best FRIEND is in love with my BEST friend! When my best FRIEND told me about that feeling a question appeared on my mind, "will my BEST friend will accept that?" A big question mark and a lot of possible answers are on my head. My best FRIEND  asked me what should be the first move. Now that I'm on the middle I felt how difficult it is to stand in a middle of the road with those cars passing so furious(get me?). 

What should I answer to my best FRIEND's question? Should I say . . . just keep it! or tell everything that you feel for my BEST friend. My best FRIEND is afraid of telling everything to my BEST friend due to the fact that my BEST friend has the possibility to get angry and their relationship as  friend will turn into hatred, anger and so many feelings that will let the both of them fall down. How I wish that everything will be fine, that their connection will still be more tight.