Should I ditch this person (long, scandalous drama)?

Sometimes friends opinions can be very judgmental, but they can also be the most help. I've gone through a similar experience as you (not the same criteria, but similar idea) the entire friendship is one sided. It's never a good thing to have, friendships are supposed to be two sided. I suggest backing slowly away from the friendship, not leaving it abruptly. I'm guessing you spoke to the friend in question about your feelings and how you feel, and still she refuses or forgets to change. Make yourself less available for her, start denying hang out session, make yourself unavailable to talk maybe then she'll realize the importance for your friendship, if not, at least you're growing away gracefully rather than through a fight or negative feelings, so you can still consider her a friend, just not a close friend, that way there is no drama between you two.