I am right there with you. My obsession is not my X, but my fear of him taking me to court to gain more time w/my children. For today, there is nothing I can do if that is his plan. So...when that anxiety creeps in, and it does, a lot, I am trying to do just what Lexie has said, replace that with something else. Get busy doing something else. Try to refocus my mind. It's hard, I completely get it.
Butterfly, it's really great you found a therapist you hit it off with, that is many times half the battle.
Many hugs!