Audiobooks+ some other mindless activity shuts my brain off really well. Find a series you love that your library has and pick up a new sudoku or other puzzle app and go to town.

If you're having trouble finding books I recommend a long sci fi or fantasy series. The Expanse is great, or Dune is also fantastically long. If fantasy is more your style maybe someone can recommend something but I know the wheel of time has a ton of books.

As for mindless things to do while you listen to audiobooks, either find a puzzle game or pick something up to do with your hands that requires few materials and is calming and productive. Here are a few that work for me:

Coloring (you can print out free coloring pages from the Internet like the ones here: https://www.crayola.com/free-coloring-pages/adult-coloring-pages/)

Color by number

Crochet or knitting (lots of good online tutorials and making a scarf is a good first project)

Modeling clay (just reuse the same clay over and over again if you want to save money/supplies)

Yoga

Walking on a treadmill or riding an exercise bike

Weightlifting with free weights at home

Tai chi

Best of luck, I know this type of thing is tough. Try to stick to regular wake/sleep cycles as much as possible and get outside during the day if you can, it definitely helps. Sending hugs and hoping things get better soon.