I think you have to give life chances, you'll never know if you'll be happy ever again until you give life a chance.

I know how hard it is to lose friends, I have accepted the fact that I can never move on. All things I shared, I can never get back. I don't think people are 'substitutable', every person is different, and every soul has something unique to offer to you as a friend. But you will find more friends soon, and it will alleviate the pain of losing your ex best friend and ex gf. I'm sorry to hear about what you're going through.