Is OTHER wrong in the post ? POST : So me (20M) and my girlfriend (21F) have been together for about 8 months. I knew since the beggining or our relationship that she is attracted to girls, which I didn’t really mind, because it has never previously been an issue for me. To give this story some background, she was on anti-depressants for almost a year (she stopped taking them recently) and they fucked her up a bit, they have some horrible side-effects and affect your behavior. I didn’t care much because I was willing to help, I knew she needed someone to support and take care of her. Now, for the actual story... She started uni again this year and she made some friends. She also met this girl (we’ll call her Sara) which is a year ahead of her. Sara is a lesbian, she dresses like a guy and that’s pretty much all her Facebook profile shows. A few months ago my girlfriend and Sara went out to talk about uni and other stuff. My girlfriend told me parts of the discussion they had, which involved Sara encouraging my girlfriend to try MDMA, because it’s cool and similar stuff. Knowing this person could be a bad influence on my girlfriend (as she was on antidepressants, which means not even alcohol is allowed), I told her it doesn’t sound like a good idea for them to hang out too much, but she didn’t listen to me. Time passed by and I realized I was right. Sara was some kind of female fuckboy by what my girlfriend was telling me. I asked her why won’t they stop talking, which resulted in girlfriend telling me she has a crush on her. I felt pretty weird, I didn’t know how to react.. I felt jealousy and I talked with my girlfriend about this but she told me I shouldn’t worry. After some time, I think they got in an argument or something and they stopped talking. Honestly, I was happy.. Girlfriend came to me and promised she’ll listen to me from now on, told me I was right and that she won’t talk to her anymore.. Not much after, she started acting weird. She didn’t want to tell me what’s wrong at first but after a few tries, she told me she really likes Sara and that Sara broke her heart. That made me feel useless. I felt betrayed..  I felt broken as well. My girlfriend and I had all the reasons to be happy but she’s sad over some hoe. Recently, I saw they were talking again so I confronted her and asked her why would she do that. She told me she feels like talking to Sara. I have to admit I got pretty upset and felt jealous because last time she was feeling sad over some bitch and I didn’t want that to happen again. I asked her if that girl means more to her than me. She said no, and I asked her why would she do that after she got hurt by that person and I got a typical response that sounded like ‘I wanna see where this goes’.  I told her she has no respect for me as she knew it hurt me last time to see her suffer over Sara and I told her to choose between me and her, and they stopped talking. 
A few weeks later, here I am again, they started talking again and my girlfriend even told her to go out. I told her I don’t want them to talk anymore but she says “it’s a girl, it’s not the same thing”. AITA? what should I do?