Hi babygirl. I know you feel crazy right now, because I have been there. Not EXACTLY there....but close.
I'm married and my hubby and I have recently fallen for Pinky. Although our situation is different from yours because I also have a relationship with Pinky, I totally understand the jealousy, panic, fear, all those terrible feelings.
All I can tell you is to be totally honest about your feelings for your gf, and your feelings about her gf. Why is it such a huge deal that your gf doesn't hurt this other girl's feelings? Seems to me this other girl is being difficult. AND she is hurting YOUR feelings. Doesn't your gf care how YOU feel in this situation?
Just my $0.02 ... you can only control how YOU feel. You cannot make anyone else love you, feel for you, or do for you.
Your number one job here is to take care of yourself. No one else will.
We love you, girl. Hang in there.