Thanks Hon. Not sure how old you are but you can use this as a learning experience.
Your friend may be doing this for lots of reasons. If she ever wants to open up then you will find out what is going on but you can't make her open up and pushing won't help. I was just at the end of my rope when I am in the same vicinity with my brother and wife and they are blantant about running away even when they think they are not.
It may be best to concentrate on making new friends. Who knows your life time friend may be in your neighborhood but you are spending too much time worring about this friend not to see them. But learn how it feels to be ignored and try not to do it to others. I think it's better to tell people you are just too busy or whatever to have the same relationship then you did have and you 're sorry when they try to contact you and you can't be with them.
I also try to be there when it comes to my SIL cause I am learning my hubby has a family and I can't dominate him so he feels like he can't see them. I try to not take things too seriously so I let go of things that are said so it doesn't escalate. It's up to us how we feel not others.