I Lost a Friendship

I am afraid it might be time for me to let go of my platonic best friend. The person who I used to share every random thought with and had so many inside jokes with. After years of vacations and nights out on the town together. This year has been one emotional argument, one right after the other. I have watched as she has slowly changed into a cruel and uncaring person. She has walked away from her faith and religion. Has told me that life has no meaning and that loving people is a waste of time. She has become bitter and ill-tempered. I told myself, that she's just going through a tough time, if I continued to be my loving and caring self towards her that she would eventually come around.
Last week she told one of our mutual friends that she thought I was irritating and wished that I would go away. After everything I have put up with, I don't know that I can forgive her for this. I haven't even spoke with her since then.