From what I picked up, CBT is basically telling a bad thought to stop and moving to a different topic. Like literally tell the idea or your thought precess in your head to fuck off and process something useful until your default thoughts are not constant nuclear war in your head.

Its a million times harder than it sounds at first, but progress snowballs. Eventually you retrain the briains default reaction to chill out instead of contatntally assuming your doom. You figure out how to extinguish a thought chain thats going to end with your brain telling you to neck rope before it goes that deep.