A friend who understands us and sees us as we really are is very precious. You sound like you are understandably grieving her loss.

You might try thinking about what you've lost with her leaving and how to find it in other places. It doesn't have to be one person, and it probably won't be. It may be a combination of psychotherapy, support groups, hobbies, opportunities to meet new people, and other things that you come up with. Those things may change and evolve as you get past her absence.

I have experienced something similar to what you're talking about. It was enormously painful. I don't connect with people all that easily, so when I do meet someone who sees me as I am and really seems to "get" me, it is devastating to lose contact with that person.

I have found that a number of activities and people can replace that to some extent. It's not as soul-satisfying, but it can be almost as good.