I used to suffer from intrusive thoughts a lot - like to the point I couldn't function at all because I'd be stuck staring at a wall for 4 hours in total agony. Therapy helped me a ton - so much my OCD has been in remission for years and I don't even really think about it anymore. The stuff I learned continues to help me deal with other obsessive thinking, anxiety, and maintaing perspective more generally.

CBT was what helped with the intrusive thoughts, and Mindfullness for disassociation etc.