You do not need to get any single thought too seriously. Why?! Because your mind is a lot like a mental playground constantly generating and experimenting with new solutions and new ideas. Therefore, no single thought can possibly define you. So you had a scary and negative ideas, or image or dream. No big deal!!! It is just your mind playing around with new ideas.
You have to remember !!! You do not necessarily get to choose your thoughts. Our mind has plenty of ideas why we always try to choose the bad one. Hence, we are the only one who would choose whatever we want which we want to act on and reflect.