Girlfriend incredibly jealous... what do I do?

So about 2 years ago, me and my girlfriend broke up, lets just sum it up and say it was because I was being an idiot. I tried for weeks to get her back to no avail. When she finally started hooking up with other guys, I figured it was over, and started looking for others myself. I met another girl, and it just so happened that the night we had sex, my girlfriend decided "she was ready to come back to me." I was with the new girl at my best friend's house whom my girlfriend called when I didn't answer my phone that night. He told her I was at his house with another girl, she came over, I wouldn't go out and talk to her. The next morning we met up for coffee, she was freaking out, I told her everything, and the next few weeks were hell, her "getting back at me" or whatever, anyways after a few months of being children, we solved our differences (or so I thought) and got back together.

The problem is, no matter when this other girl's name comes up, or anything reminds her of her, she FREAKS out. Recently (past year or so) things have been very very good however. She went to school in another state a few months ago, and we had planned for me to come out there and move in with her. This is supposed to happen at the beginning of next month. She recently saw on facebook that a friend of mine was a friend of this girl, and completely LOST her shit. I'm not her friend on facebook, I don't talk to this girl anymore, I have no interest in her or anybody else for that matter, yet this set her off. She has since been freaking out for almost 3 days straight, being depressed, barely eating or sleeping, getting drunk and sending me horrible texts and voicemails, but then calls me crying asking me why I did those things to her.

I'm very confused as I don't understand where I went wrong. I figured dating another girl after she had apparently made it clear to me that she was no longer interested in me was fair game. She's asking details. "Where did you **** her? Did you like her piercings? Did you like her tattoos?" It's very uncomfortable to talk about and I'm tired of hearing it, but I've been with this girl for 3.5 years and love her to death.

What the hell can I do/say?

Thanks for reading

She needs help growing up. I suggest you make therapy a condition for you remaining together. You didn't do anything wrong, so far as I can see.

I think she never thought that you could actually be attracted to someone else.
You have shattered her self confidence. She has to come to terms with the fact that there is a possibility that you could like someone more that her.

If you want to help her....and to rebuild the relationship you need to make it clear to her that she is more special to you that the other girl. You might even need to cupt all contact with this person in order for your gfriend feel safe again loving you!!!

The exact same senario happened in my relationship, although I was in your girlfriends situation. I can understand how she feels and even though you had recently split, it still feels like a betrayal in some respects. It will take time to repair the trust with your girlfriend but we are living proof that it can be done. If you love her enough it will definately be worth the extra effort.
Good luck.