Who wins when both lose?

So I've decided to distance myself from one of my friends. She just keeps using me for rides and as a messenger between her and her gf, and keeps hurting me. However now I feel like I'm hurting her because instead of talking to her about it I'm just kind of ignoring her. I have always been the person to put others before myself so this is in a way hurting me even more. I just can't win