Yes, I've been where you're at, and sometimes I'm still there. I hope that CBT will be helpful to you. It may be that another kind of therapy would be better to get at what's underneath your obsessing, but with someone more experienced than your former T.

The ways I've learned to stop obsessing are, not in any particular order:

1. Don't try to stop because it doesn't work.
2. Instead, get busy with other people and/or activities in your life.
3. Tell your T what you're doing. If CBT isn't the way to help you, he'll tell you.
4. Do yoga or exercise, preferably in a class. Or swim. Something physical.
5. Connect with at least one person other than on PC every day.
6. Volunteer somewhere.
7. Learn something new, like a new hobby, a new language, a class, or something to keep you occupied.

The obsession ebbs and flows, like any other feeling. It won't go away until you replace it with better things in your life. I'm not an expert; I'm still a "work in progress" but I'm getting there. I hope you find your way too. You're NOT alone!