First of all, don't answer all of her messages if it's not necessary. Forget about the friendly banter. There is a time and place for it and now's not the time. Obviously your health is suffering because of it.
If she messages you, respond with "hey I can't talk right now, I'm out. I'll get back to you later." Then turn off the phone.
Show her you've moved on. Where is she living now?
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.