You have come to realize that you made a hasty decision back then.
You broke up with her in the midst of a heated argument.
But when your anger subsided, you realized your mistake.
You are thinking now of how to get your ex-girlfriend to want you back after that heated moment.
First of all think back at what you have said during that heated argument.
Anything that you have said to her that may be interpreted as personally insulting should be weighed for the effect it had on her.
Consider her feelings about the break-up you instigated and what you could say to her to alleviate the pain those words and action had caused.
The best way is to make an immediate approach to apologize for your bad behavior before she finds solace in the arms of another man.
Approach her with utmost humility and ask for forgiveness.
It would help your cause if you would bring flowers or something she would appreciate as a sign of repentance.
You should say your piece in front of her, but do not expect or insist her acceptance.
After you have conveyed your apology, leave it at that.
Communicate with her often to ask how she is doing and if there is anything you can do for her.
Be casual and friendly in your conversations with her.
Make her feel that you are concerned for her.
Be available for her.
You know her routine, so you know when she would likely need your help.
Fetch her from the office.
Help her with the grocery shopping.
Give her your companionship and recapture the camaraderie you shared.
Most importantly, improve yourself.
Get rid of the childish and irresponsible behavior that tends to irritate her.
This will take awhile, but show her that you are doing something to improve yourself.
Enhance your appearance and change your attitude.
If she has been nagging you for that long hair, have it cut and buy some decent clothes.
To get your ex-girlfriend to want you back, make her proud of you.
Adopt more mature attitude towards life and relationships, now that you have learned some lessons on how your bad attitude can lose her