Wherever you decide to tell her, I would just be totally honest. But when you're with her, don't just blurt it out, ease into it. Talk about something mutual for a while.
Then when you get up the nerve, just explain to her that you have to tell her something that's been on your mind for a while. Also (like I said) be honest, let her know before you tell her, that you really value her friendship and no matter what, you hope it doesn't change that and you just have to get it off your chest.
Then..(whatever it is you're truly feeling) just tell her everything. Just tell her man because mark my words, if you don't then you will be kicking yourself later down the road.
It's better to be truly honest and out in the open with your feelings and then getting shot down, rather than keeping it to yourself and years later, you are stuck forever with the thought "what if" and I'm telling you, that will stick with you and hurt a lot worse than getting shot down in that moment.
I mean if that does happen, of course it will suck and honestly you might feel like crap for a while. But in time, I promise you that will pass. But not doing nothing.. forever wondering... that will stick with you and you'll feel a lot worse.
And who knows, if she ain't interested (now) just remember, people change... if she truly is the one for you, it will happen one way or another. Your paths will cross again, but hopefully you both can stay friends in the mean time.
Just go for it now while you still can. Be honest with both her and yourself and let nature take its corse. Whatever happens man, good luck. I hope all works out for ya buddy!
P.S. don't ever leave the forum dude. It really would be a shame to lose you. A lot of people are here for you