Girl messes me about, what do i do?

i was dating a girl called m for a while but she was crazy and treat me badly. after not speaking for a month she invited me out for a drink with her and her girl. m treat her other girl badly too and they broke up. i met her ex and we just clicked and started seeing each other. my girl c, we were so smitten with each other. but our mutual ex has ruined things by being so threatening towards c because she wants her back. she beat c up last week. c tells me she loves me then says she doesnt want a relationship then says we are ineffible then says she wants me then says we are just friends. it hurts me that she is secretive about us but shes scared our mutual ex will find out and hurt us. every day i get told something different about how she feels about me. i got very angry today because she is having a weekend away with another ex of hers who is now one of her close friends but they share a bed and that makes me uncomfortable. im so confused.