Voner, whatever you're planning to do about it, good luck! just
some caveats to bear in mind:
take it slow, don't try to rush and stuff. are you very sure you
like her in that sense? or could it be just this closeness that you
share? i've had some close "sisters" before, and really did ask
myself whether i have feelings for them in that sense. most of the
time, it's really just this loneliness and closeness you feel for
her that tells you you like her. well, i really shouldn't comment
too much, because i don't know what your situation is. just think
about it okay?
whatever happens, bear in mind that you two have a great
friendship, from what you've said. so no matter what, preserve it,
and not let things sour. a long lasting relationship is based on a
good friendship, and understanding between 2 people that you'll get
in a wonderful friendship. no matter what happens, don't lose that
friendship. it's a very sad thing to happen.
and if you're sure you like her, then go for it. but don't be pushy
or something. don't play guessing games and stuff. just be honest
with her. ask her out for a nice talk, and you can tell her about
it. if she tells you that it's not what you're thinking, just take
it well, and who knows, you can build upon it. good luck man! hope
i made sense. 
