Slowly Ending A Toxic Friendship

I feel sad and like a loser. I've decided it's better to slowly end my communication with my longtime college friend. We used to be super close. She helped me a lot and gave me life advice. I'm an introvert so I have trouble making friends. But through recent years, I've noticed she became toxic. When she had problems with her ex boyfriends, she would call morning and night, then I'd give her advice. But then she will always get back with them or be in another relationship. One time, I got busy with college life and was depressed, but she blamed me for not being there for her and told me I should know when to support her. Another time, her new friends started a rumor that I was dating her guy friend, when in truth, she was the one who told me to hang out with him since he needs friends. During that time, I was dating my now fiance, and she told me that I was lying to him. My fiance did not believe her. Eventually, I went to her place to salvage our friendship. I let her stay friends with her guy friend and toxic friends. She's always late when we invite her on hang outs and whenever she calls it's mostly about herself. I now barely talk to her. But I feel sad losing my only friend. Now I hang out with my family, fiance and his friends. I also focus on my life to forget the pain.