I think it would be in your best interest to back away from this friend for a little bit. I know it hurts, but people change, especially at the age that she is. At this age, a lot of girls (myself included at that age) put a lot of importance in guys. I did the same thing, started dating a guy that I couldn't see wasn't a "great" person, and I pretty much stopped hanging out with all of my friends to spend my time with him. It wasn't anything personal against my friends, I just had tunnel vision. As much as it hurts, and as much as I know you need her, you have to pull away for your own sanity, at least for right now. Maybe hide her feed on Facebook so you don't have to see those pictures, or limit your time on social media. You don't have to end the friendship, just back away for a little bit. We're always here for you.