Unfortunately, length doesn't mean anything in a realationship. I had a best friend since 3rd grade who ended up being the most toxic person in my life. It took me until I was 22 to completely get her out of my life. All of my friends who backstabbed me when I was having psychosis had been my friends for 10 years.

It was extremely painful when I lost them all at the time, but in the end it has been much better to be without them.

True friendship is measured by loyalty and reciprocated care, not by games of "he said/she said." If she was really your friend she would hear your side. And she would attempt to make some amends or meet on common ground.