I went through this recently. Exactly what you went through. Combined with the intense feeling that everything is meaningless. No amount of reading did anything

I went through this recently. Exactly what you went through. Combined with the intense feeling that everything is meaningless. No amount of reading did anything for me. I tried to change my views and everything, but nope. Then I went to a psychiatrist. Got prescribed benzodiapenes. Two weeks on it, every existential thoughts vanished. I felt normal again. Then my doc stopped it. Got some severe withdrawals from the benzos. I would never ever touch benzos with a 3 foot pole again. Even after 3 months of leaving benzos I have some bouts of anxiety. I use Ashwagandha regularly. To me it's been life changing. The thoughts don't completely vanish but even if it comes, it makes you feel meh. Also travel. Traveling a lot helped me. Made me focus outwards rather than my inner voice. Traveling, going out a lot, Ashwagandha and talking to people is what's helping me by a significant amount. I am not a native speaker, so if anything confuses you please ask away :)