This sounds very familiar to a situation I went through...best friends for 20 years but more and more becoming more distant and leading other lives. I could handle it, and just hanging out occasionally, but she seemed to want to be clingy best friends or nothing. As time went on, I became increasingly more anxious interacting with her because she was always blowing up about random things and making things awkward. It was clear the friendship was unhealthy but I kept in contact since we had been so close for so long. When I got engaged, I felt like I had to call her even though we had not talked (besides texts/FB) in so long. She didn't seem happy for me. Eventually when it came out I was having a destination wedding she wrote a long email hoping that she could be come/be in it. At that time it was too little too late, and I was struggling with even just inviting her as she had a falling out with my close group of friends- none of them wanted to spend an intimate week with her. So after responding to her email, the next day I was unfriended from facebook. And we haven't talked since (the first day I was so beat up about it but then I realized I was so much better off)
Anyways, realize that your "friend" obviously has issues of her own and it had nothing to do with you- that is what took me years to understand. She will have to live with knowing that she let you down. And now you have makeup money!