Write an article based on this "See a therapist. Call a family member. Consult friends you don't have in common with your lost friend. Be mindful of your mutual friendships. Don't bad mouth your lost friend."
If you are really having trouble moving on it can be helpful to deal with these feelings in a professional setting. A trained therapist will be able to listen to your perspective of what went wrong in the friendship and help you learn from mistakes. When friends are the problem, sometimes turning to family can be a safe solution. If you can, try to call someone you think has gone through similar friendship breakups in the past. Perhaps a parent or grandparent with more life experience, though any family member can be an enormous comfort. Reach out to people who don't know the friend or friends you are no longer hanging out with. They can listen to how you feel and offer an objective perspective on the situation. Let them know how much you appreciate their support. Remember that even though you may have lost a friend, you are still not completely friendless. Mutual friends may not be the best people to reach out to if you feel like you really need to process the loss of the friendship. This puts your shared friends in an awkward position. You'll also run the risk of alienating more people if you are perceived as trying to get people to take sides. That said, you can still reach out to these friends for companionship. It can be a nice reminder that you still have people that care about you.  Avoid mentioning the friend that no longer wants to hangout with you. Try to focus on the things you still have in common with your current friends. It can be very emotional when a friend says they do not want to hangout with you anymore. Avoid the temptation to talk badly about them or tarnish their reputation in any way. When the emotions die down you may both realize that the friendship is actually salvageable. It may even come back together stronger after a disagreement of this magnitude. You don't want to make the situation any worse or lower any chances of the friendship being mended because you bad mouthed someone behind their back.