Start to back off, do the fade till eventually, you don't talk/meetup at all. Sticking around to be her emotional tampon will stagnate you from having a clear head/emotions to look for someone that wants a romantic relationship with you.
You can't remain platonic friends with someone you want more with... it's just you torturing yourself while she sucks you dry (and not in the good way).
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion