We've been close friends for years. She betrayed me deeply and talked bad about about me to someone I was very fond of. I was the first to acknowledge the issue as she was happy to ignore it and carry on with her daily life. She apologised, although I would consider it a weak apology for what she did. I have so much anger inside me and I want to let it go for my own sake but I really don't know how to. I'd really appreciate any advice.