Sometimes we don't let go of our friendships, we simply outgrow them..
This seems true in your case.
I am saying this because I can relate very well to this. I used to do it as well. You know ***** about how unfair the world is to us and have long useless conversations about our miserable lives. But after a long time or should I say years, I realized that being angry at the world isnt the way ahead. How can the universe love me, when I don't reciprocate the same feelings. So I decided to get better. Mind you many things are easier said than done. It is tough to be optimistic about everything around us when your life is going downhill.
It's a lengthy process but it is definitely worth the journey..

I feel like this is not the answer you were looking for
But definitely felt good to rant after a long time :P