I am still on Facebook because it’s the only way I can stay in touch of relatives, including my ASD brother who has decided I communicate with him either through that or Quora. This is how I have survived it:
Heavily curate your friends list and mute anyone you don’t want to see after only a handful of unpleasant posts.
Only join groups that don’t get overtly political unless you don’t wish to participate and just want to lurk.
Just don’t argue with people on your friends list and don’t engage in arguments that people try to engage you in.
Tell Facebook that you don’t want to see any ad you find personally repugnant. You’ll still see ads, but they will be less awful.