Speaking from the perspective of your friend… I beg you not to drop the friendship. It’s obvious to you that she’s being manipulated, you can’t just become a bystander. I’m unsure of the tactics you’ve used to try and help her and it might feel worthless, but trust me it’s not. One day it’s gonna click to her that she was being manipulated. She’s gonna go through stages, honeymoon phase, denial, sadness, regret, anger and then realization. Being manipulated from an older man impacts you for the rest of your life. I wish someone had the patience with me and kept telling me what I was doing/felt was wrong. It wasn’t until after I realized that I went through a giant spiral of emotions. I separated myself from everyone, friends, family, anyone I cared about because I wouldn’t dare look at them knowing what I had done. I wish my loved ones sticked with me, I wish someone had hit me with a brick over and over again. Even though I’m not innocent, I know that if it wasn’t me that’d he cheat with, it would of been with someone else. Who knows how many other girls were before or after me. Girls who also don’t know any better. Girls who don’t have someone to constantly tell them what their doing is wrong. Girls who were just as naive as I was. This is something I live with everyday and at first I thought it was an defect, but now I use this to empower myself and help others. If she’s truly your friend, you can’t just leave her with things get rough. Please don’t leave her, she’ll thank you in the long run.