You sound like a very creative spirit and that can be a beautiful and positive thing but this sounds like a heavy mental load to carry on your mind, you would certainly benefit from practicing Void Meditation (you can try this throughout the day, holding a crystal and feeling it's energy, or watching the leaves blowing in the trees, I also love listening and watching quiet ASMR for winding down my brain like sound bath and other ASMR - but avoid subliminals or falling asleep to whispering) as it gives your brain a break from racing and intrusive thoughts.
While it is true that what we dwell on often we can manifest, this is quite a process and more unlikely than you think (prioritize cleaning and purification meditations before doing too much empowerment as you have to gain a better control on your mind) and don't stress over this too much and blame yourself as this can only reinforce negative thought patterns and cycles.
Let go and don't worry or identify with unhelpful and unconstructive thoughts, we all have those at the start.
This is an excellent Pythagorean meditation by High Priest Zevios 666 to take control over your internal stream of consciousness: https://ancient-forums.com/threads/introspective-meditation-increasing-conscious-awareness.63176/
This Sermon by High Priestess Lydia could help you pertaining to obsessive thoughts?
https://ancient-forums.com/threads/obsessions-detach-sublimate-manage.291217/
Perhaps channelling this creative thought-flowing tendency towards more material and grounding exercises, like writing fiction using firm writing structures as opposed to free-writing, could be beneficial to getting a rein on your mind?
Identify when you start to dissociate into your thoughts and do something concrete and physical (this can be anything like going for a walk with a friend, petting an animal, reading about something you find very interesting, learn a language, do puzzles, learn a craft like crochet, opening your journal/notes app and type a paragraph/say quietly to yourself about how you are feeling in that moment, e.g., fearful, frustrated, disappointed, bored...)
You can get a grip on your internal streams of consciousness and have a peaceful mind, you have to believe you deserve it. Don't identify yourself with any negative unhelpful thoughts (our thoughts can be products of dross on the soul, societal/religious programming, old fears and worries --- not "truly your own") and eventually it will calm down.