Autism, especially higher functioning, often comes with clinical-level anxiety. Definately talk to a psychiatrist and therapist. If you’re already on anxiety meds that aren’t working, try a different one. Keep in mind that the wrong one can cause suicidal thoughts. They vary quite a bit, and new ones are coming out all the time. You’ll eventually find one that helps take the edge off your anxiety. That will help you cope with the other things better. From my experience, things also get naturally better as you age, so there is light in the tunnel.

Edit: One other suggestion. Do the bad thoughts come at night? That’s also common. If so, try going to bed earlier - before they get a chance to get cranked up. Wake up earlier so you can have quiet time doing something peaceful like sipping coffee.