What has helped me immensely with catastrophic thinking has been DBT. CBT has not really done the trick for me in regard to my constant catastrophic thoughts.

But DBT (dialectical behavior therapy) helps with emotion regulation and distress tolerance and helps with techniques to (my words) "stop spinning" before the thinking gets to "red zone" levels. Or, if I reach the red zone level, it helps me to get out of it more quickly instead of ruminating and making it continue.

It has really helped me. It's a huge time investment, but worth every bit of it. I still have my issues, but it helps me cope, and people have noticed the changes.