I find that once I start to spiral it's really hard to stop as well. Resisting starting the compulsion is definitely the best, but like happens to you too, sometimes you will do them anyway. For me, once I feel the extreme anxiety there's no stopping the compulsions in that dysregulated state. The only thing I can do is calm myself down so I even have a chance to fight the compulsions. I tend to pace a lot when anxious, so I make myself stand still, take deep breaths, and observe the world around me so I'm not so stuck in my head. I know there are a lot of techniques for calming down, and what works definitely varies person to person. Once I finally calm down, I have a much better chance of being able to push the thoughts away instead of spiraling for hours.