I just want to type out a kind and soft notice: Here in Fishlore, we do not call any of our fish or any fish 'stupid'. All fish are unique in their own way and although they might not be smarter or nicer than the other, they are still fish and living creatures which we should take account and care for.
I know you're having trouble with your Angels. But that's their behavior. Shawnie has given some great advice above, so best of luck!
Also, if you want to have tetras, I'd advise having a tank just for your tetras. It would look great as they love to school and sometimes school altogether, not just their own kind. Example: Neons with Cardinals, or Glowlights with Rummynose. My Neons, Rummynoses, and Glowlights all school together in one group, it's beautiful!