My psychologist has told me that generally intrusive thoughts are things that the person would NEVER dream of doing. Recognizing that it is an unwanted intrusive thought is important. The fact that it scares you shows that you would never do that. The goal is to become desensitized to those thoughts where you can just brush them off as intrusive and know that they are not your true desires. I've gotten to that point with intrusive thoughts: I'll have one from time to time, and brush it off and just keep doing whatever I was doing. They are not "of me," that is, of my true desires. Do you have a therapist you can talk to about this?