How did this happen?

How did I get in the middle of the drama? And why didnt I see it before. Ive been there, the person that is just the best friend when two of her friends are flirting and getting to know one another, it sucks and I never would wish that on my worst enemy, yet it seems that I am doing almost the same thing to one of my friends. The flirting, though is just one way, and it directed at me which is almost worse.
I am sorry that this is happening, you know, its not what I wanted to happen, and the hardest thing for me is to talk to him face to face about this. It is so hard because of my past, but I have to get over that and soon, not because I need myself to do this but because I cant lose the friends that have helped me through. I would do anything for them, even the thing that for me at this moment is the hardest thing in the world.
I have tried to tell him over and over that he isnt for me, others have tried too, and I hoped that it would work that way. It seems though that this boy is much more hardheaded and either doesnt hear us or wont admit it.
I never thought I would be this person, just because I was on the receiving end for so long. I never imagined that I would turn someone down for all the reasons that I was turned down. And its even harder for my mind to wrap around it because I have felt both hurts before. I know how it sucks to be turned down, being told that you are just a friend. But I also know that I have to do this, I cant drag it on, because that will just make it worse in the end.
And I know how it sucks to be the best friend of both and see this happen, although for me the interest was both ways. For me the scarring moment was at my birthday party, and people were playing hide and seek, Katie and Tim couldnt be found and then his brother and my best friend Matt went to look in the barn. When they got to the barn Tim was apparently pulling up his pants. I would never betray anyone like that, because I know the pain.
So if you are reading, my promise is this, I am going to do the best I can at reinforcing the friendships that I have and making clear that I dont want anything more. I plan to do this by sitting him down and crying it out if I need to. And I am only crying because I feel the pain that he is going through, but you will be there to comfort him and we will all get past this. We will kick the elephant out of the room! I love you dearly and I would do anything for you.