Am crazy about my gfs best friend :( ??

alright i get this sounds bad, first let me start by saying NOTHING has ever happened at all between us. I just dont know why i feel this way and cant get it to stop, Me and my gf have been together for years, and I've known her best friend longer then her, in fact i met my gf through her. But for the last few years i feel this weird powerful connection with her and it actually drives me nuts, we get along great, in fact ive made it a priority to try my hardest to make her mad some times just so it will ease the tension and make it easier to avoid doing something dumb or saying something. I love my gf, i really do, i would do anything for her at the drop of a dime. but for some reason whenever i see her friend or am around her at all we click, i get this weird feeling she feels that way too but not exactly sure what to do. because the feelings only get worse and grow over the last few years and im scared its gonna get to the point where i slip up and say something or do something without meaning to. at the same time i dont want to throw the elephant in the room and risk hurting my gf over feelings that have never manifested into anything.. does anyone have any advice? should i just leave it alone and continue to rack my brain with "what ifs"? or should i find a way to figure it out without hurting anyone just to get some closure? if so any ideas on how i would do that?