Maybe you can still work things out. The obsession is YOUR problem and I would hope that she can find away to help you with it. It sounds like you have suggested cutting ties as a way to help yourself with the pain? Maybe she can help you find another way? Or maybe she will agree with you that is the best thing to do. You can't know for sure until the session.

Congrats to you for bringing the issue to a head as it sounds like it is pretty difficult for you right now.