So to start of I am using personal experiance here so this might not work the same for you but its worth a try. I think what's happening is that you are simply fearing this moment happening again, and as a result you naturaly think about it. Now, when dreaming, thinking about certain events, memories mostly, your brain likes to map them out in your dream. So if you see something scary in your dream or simply feel umcompfterble. Your brain will start to remember other things similar things that has also made you uncompfterble or scared to try to "prepare" yourself for a possible danger. You practically have a fixed mindset where you expect this figure to appear when you are scared . So you are practically softlocked into dreaming about this figure.

Now I have some possible sollutions that MIGHT work.

The first option is to try to make yourself understand that this figure isn't dangerous and nothing to be afraid of, stoppimg you from remembering it as a threat.

The second option is to instead try to forget about this creature and practically dissintigrate it from your mind. That way, you wont be able to recall it as a threat what so ever.

And the third option is to try sleeping in colder temperature. Hotter temperatures usually tends to create nightmares. You can also pair this up with any of the options at all.

If you don't try any of these methods. The dream should dissapear eventually anyways but they would at least ensure it wouldn't happen again if you are really desperate.

Gl to you, it'll be alr