You're kidding us, right? Then what does she do while she's focused on the phone trying to make the call when he comes charging at her?
I was thinking it could be the perfect murder. She invites the target of her hate home then kills him. She then lies with this story afterwards.
If he makes any move in her direction, she is then perfectly justified in shooting him. One other commenter noted that he lunged at her. I had missed that detail, which makes all the difference.
If he had not lunged, and ifshe had told him to return to the closet and close the door and that, if he came out, she would shoot him, this would have taken her out of any danger while she waited for the police to show up.