<human>: Can you condense the text into three sentences or less?

I'm no native speaker, so please excuse some inevitable mistakes in my grammar or choice of words. 

I'm relatively fresh (about four months) out of a LTR that lasted a little above five years but found a rather quick ending, which is mostly okay for both of us.  
Now there is this girl I know for a very long time, went to school with and always liked very much as a friend. While we always had a rather flirtatious way with each other, i feel like she's making some serious moves since I broke up with my ex. I have to admit, that I'm falling for it... and her.

This would be great - except for the fact, that she's been my best friend's crush ever since they first met in junior high school. In the past I always hoped they'd get together, but as years went by it became an unspoken truth in our circle of friends, that he'll never get her.  
She doesn't hide the fact, that she's not at all interested in him and he seems to live well with being rejected - I know, that he most certainly doesn't and I talked to him about it in the past but in the end it has never been my decision.  

Now that I'm uncertain about my feelings towards her, I would feel very uncomfortable in talking him out of her. And with "uncomfortable" I mean, that this would be the last thing a best friend should ever do. 

I just don't know how to react to the whole situation. Should I tell her, that I feel flattered by her approaches (which would be an understatement) but value the friendship more? Should I first talk to him about finding a solution?  
After all I'm not completely certain, that he still crushes on her. We visit different colleges and don't talk as often as we used to and, well, being boys we never really talked about relationships and the matter.

Did anyone experience something similar? How did it work out?  
I'll appreciate every comment.
<bot>: I feel like falling in love with my best friend's (hopeless) crush for nearly ten years and don't know how to approach the situation.