I still think you are too worried about what she thinks. If she feels that having conversations keeps you hanging on to hope, is that your problem? You can't help how she feels about whatever, so don't worry about it.

Do whatever you feel like. If you are concerned about her son, then call and see how he's doing. Who cares whether she thinks it's pursuing or whatever.

Other than that, ignore, don't ignore her, it doesn't matter. Just show your indifference to her. Be yourself.

You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer