I agree . Fantasies are things we can “ think consciously of” or reveal themselves in dreams. The unconscious plays a huge role in trying to “ balance “ our real conscious life. Intrusive thoughts just pop into your head , unwelcome. They can try and control how and what you think about. Some can be good though I believe , like an idea ! A bright idea. Or an answer to a dilemma. BUT, if they’re negative then we need to get them the hell out of our heads by replacing that thought with another. TWO thoughts cannot occupy the same space at the same time. Try and take control of your mind. Try mindfulness. Concentrate solely on the present. It could be as simple as looking at a beautiful picture. I mean REALLY look at it. The past and future do not exist right now.
The main thing is that you don’t act on your negative thoughts. Don’t give them power.