MY EX FRIEND IS USING MY CURRENT FRIEND?

Ok so we are all 14 and my friend now ex friend used to be so sad and everything and cut herself and was raped by her brother or so she says i'm beginning to think she was using me to get some sympathy or whatever i don't know but now she plays it off innocently in front of my friend but i can feel the tension and my current friend we'll call her Ruby (which is not her real name but it's easier) ok so Ruby is a care free, naive, innocent child minded 14 year old girl which are qualities that make her a very good friend but my other ex friend seems to be laughing and smiling much like we used to and it hurts i know i sound like a sappy gay person but i'm not it just makes me feel VERY bitter right now we are in a facebook convo which i'm trying to keep from turning ugly i don't want a war i want a truce ok i'll leave it there