While I am happy to offer a technique, I would encourage you to get yourself a therapist first. While the technique I will explain to you can offer some relief, it is best employed with the help of a therapist who can help prepare and follow-up. The fact that this breakup was so dramatically intense and difficult for you is worthy of investigation in therapy. There are several elements here that should be discussed so that you can cope and move through this incident, and then be sure you can deal with future relationship concerns.
To deal with the current loss you’ll want to experiment with psychodrama. Again, the best way is with an individual therapist guiding you, but the technique is one that can be used for endings that lack closure.
Begin with two chairs across from one another. Sit in one and imagine your friend sitting in the other. Take a moment to realize this scene.
Then make an amends to your friend. Say what you’d want to say to the empty chair. Then reverse roles and become her. From that role answer back what you think she would say. When this is done return to your chair and say the last thing you’d like to say. Be sure to begin and end in your chair, and you can do the role-play until it feels right.
This should help. If using empty chairs isn’t your thing then write a letter to her THAT YOU DO NOT SEND. It is important to respect the law. But you writing the letter allows you to express your thoughts and feelings. Your psyche won’t know that it wasn’t mailed, in fact you could shred or burn it once you are done. If you like you could then reverse roles (with a different paper, pen, or computer screen) and write back to you as her. When you are done send her one last line from you to end the encounter. Again, always begin and end in your role.
Hope this technique advice helps and please remember that working with a therapist as you do this is the best way to go. To locate one near you you can use the find help tab at the top of the page. And there are our forums if you’d like to connect with others online.