I know exactly what you are goin through....I am 100% with out a doubt in Love (i have never used that word other than with her and my first GF) with my best friend, and see is seeing some clown whom i dont trust nor do I really like due to certain circumstances... I have tried getting over it but that dosent work..... I have told her how I feel, and she tells me 'o, i know u and I would be perfect for one anouther, but i have to see this through' and 'If you would have asked me 4 months ago if i had feelings for you i would have said nothing other than friendship, but i now do have feelings for you but not as strong as mine for him' and 'i could see me and you together me in your arms watching the sunset and talking' and my personal favorite 'I do love you, like a brother....'
she sends so many mixed signals, like when I pay attention to another girl, right away that girls a B!T(H or a WH@RE, or ugly and she gets pissy....... she'll have me give her foot rubs and back rubs in front of this kids she dating, she tells him (while she's completely exhausted and out of her head) 'Jerry's a better boyfriend than you....' but she also tells me that she wants to marry him, that she loves him, and she slept with him after 2 weeks....
Me and her are so close, and her BF hates it, her parents think we should be together, our other best friend Angel has even told me there could be a lil hope... i have tried to get over her, but my feelings are so strong for her it kills me to try and play nice with her BF cause i know he'll hurt her in the long run......

so given my experiance in this situation.... fight for the man you love.... Kiss him, on the mouth romantically... if he's ur friend he may be wierded out a lil but he brush it off, and he may just realize he likes you too, if he flips out apologize and say you dont know why you did it, just fight for him if you love him as much as I love my best friend... and remember if you do love him and it is a no go with u 2 still be his best friend and be happy for him that he's happy even if its not with you