Strong feelings towards close friend

I know this one is a loser, but I have a very good
friend whom I've felt a strong attraction to for many
years. She's told me she isn't interested many times
(originally a friend who I spilled too let it loose to her)
and she's very condescending towards me (though I've
started treating her as a wetstone in recent years to
hone C&F with good success).

A few months ago, I started getting mixed messages
from her. She was dressing down when we would hang
out (a LOT) putting on makeup during our convo's,
constantly hovering around the topic of sex, and I got
the feeling she was at the very least looking for fun. It
was as if her body wanted me, but I couldn't seem to
get her to make a move.

Im really uncertain what to do. I want her, and I've wanted
her for a while. She's been single for four years. I've been
trying to use her to develop my game, and get my confident
around really pretty women, but it causes me a lot of grief
that I can't seem to hook up with her. Is it a pipe dream to
think this is possible?

Also, I have been working on other women and learning
stuff in the meanwhile. Its just a source of pain that I can't
get with the one I want.

Any thoughts?