I am really sorry to hear that your needy friend cannot stop bombarding you. It sounds as if she is terribly lonely. You should pray for her. And despite her annoying behavior, try to see the good behind the actions and remember sometimes why you were friends in the first place.
I believe that each of us has a responsibility for our own life and to that end, you sometimes have to let people go. There’s no need to tell others about the situation unless they specifically ask. Just tell the friend that you cannot entertain her constant texting and that you will be pulling back. If she goes crazy, so be it. You cannot control anyone else, only yourself and it is tantamount that you have peace in your own life. If the friend cannot or will no understand that, you have to cut her loose.
It’s a sad reality that not everyone is meant to be in your life forever.