ok, just don't try to make her jealous, for example we tend to say that we got another girl and she's awesome and shit (when it doesn't even exist), if she's playing with you to make you to change, show to her that you are actually changing like she wants.
One thing that you can do is talk about the past (only positive things that happened), for example when you first meet, when you first kiss, and then say: "I know that i deserve it but I miss those moments and we only give value to the things when we miss them : ("... but
now is not the appropriate time, the situation is too fresh yet and you don't want to push and force it, give time to talk about this situation.
So at this moment, don't say that you miss her, don't say that you need her and you are in pain, etc. from now on you must focus on her, ask if she's ok and if she's having a nice day... now you have to focus on her and stop complaining about you and only thinking about you like if she doesn't exist -
this it's your first step.
More tips you can start to do now:
- Don't talk about pain and shit.
- Don't let your friends talk to her about this situation, they don't help, they just screw it, believe me.
- Don't complain about yourself to her.
- Practice sports and shit to make you fit
- Update your facebook with pictures of your new changes to let her notice that you are changing (for example if you clean your house, if you go to gym, etc..)
- Remove (or hide) actual facebook pictures that show that you have low value (for example: drunk pictures, etc.)
- Don't remove any photo that have you both
- Don't change your facebook main photo, even if the photo is about you both, don't change it. Only change it if the photo gives you low value (for example: drunk pictures, etc.) in this case select a picture of you alone doing something interesting.
- Don't post depressing shit on facebook like those hipsters pics about "how you loved your GF and now i lost her" and shit, also don't write about that kind of shit, that's childish and you want to show to her that you are a man with value!
- Never take pictures with another women and post it on facebook. From now on, your pics are about friends or just your self doing cool\great things.
- Never talk with another women in public facebook messages, if you want to talk to another women then private with her.
- Post things on facebook that she might like you to post about.
- Don't post on facebook romantic\pain songs
- Text (don't call, just text) her every days (to avoid her to lost contact with you) but be short as possible on your conversations (since you want to talk to her every days you don't want to suffocate her), don't send her more than 5~10 messages, give some gap of time in between and always say that you have to do something and can't talk at that moment, like: "Ok, glad to hear that. I have to make dinner, talk to you latter" - you can make other excuse better than this, use your imagination

- Day after day you can increase the amount of messages send by day, it's good if you start with 5 and on the other day you can send 8, after 12, and so on... but do it slowly and don't force it!
- Don't show that you are alone and you need her or other person's company.
- If you go out and she knows it, then just say "meh it was boring, i'm getting older for this" - cuz you know when guys go out in this cases is to get another woman, make sure that you didn't like and you were almost forced to go out.
Note, if she's not a facebook person then try to find a way to make her notice that you are changing without telling her directly.
After some time passed (at this point you have to let her notice that you are changing - list below) you can escalate on the conversation to make you able to talk about the past thing that i said above, then tell her that you (both) were perfect and you are kind of an asshole because you didn't care much about her.
Do it in this order (the order is important, don't change the order!!):
1º Talk awesome and wonderful things that you had before
2º Lower your value to her: Say how stupid you are and how you miss those moments
3º Give her value saying something like: I'm stupid because i missed the girl of my dreams
it's like when you want to give a critic to someone, you always should start with a good positive thing about the person and then you say the negative thing, like: "You have a good positive taste of style but i'm not sure about that t-shirt", instead of: "i don't like your t-shirt".
Always do things with logic, first you have to show that you have changed, and only after that you'll be able to try to get her back, otherwise you'll just screw it more. The reason is: She only accept you back if you change, and you know that, so why would you try to get her back with her knowing that you still are the same "bad person" that you were.
If this doesn't work my friend, then you don't have another opportunity.
So don't force things and make sure that you do the right way. Also don't bring friends to this, this is just about you and her, you screw it, you must fix it and only you know how to fix it.
Oh, and no matter what happens, notify me about what happened by private message here on forum.
If you want some help, you can private message me but please be short as possible and don't use it to complain about how bad your life is, just ask me what to do and i'll try to do my best. But i totally recommend you to use this forum instead of private message me, it's always great to have a lot of different perspectives.
Best of luck!