I agree with seesaw. This so-called friend could also be using FB as a weapon posting stuff that she knows you will see and be hurt by. Honestly it's sad this behavior is occurring between 2 people at a church. Maybe this "friend" needs to ask herself why she's acting this way to people who share her faith. At any rate, this person is not a friend. I'd unfriend her immediately on FB and keep interactions with her to a minimum. Give her the least amount of attention as possible as she's not worth much and focus your energy on people that do matter.