It's hard when failed friendships can't be dealt with amicably. It's a very difficult thing to let go of...so many painful feelings involved. I think it's best usually just to go silent and allow the wounds on each side to heal in their own time. If your friend hasn't contacted you i suppose it's best just to accept their choice, focus on your own feelings and how you'd like to move forward. There will be other people in your life, more transience, but plenty of good times ahead too.