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.
Cisgender woman here, I just wanted to add that if my husband were to come out as trans, that would not be a tragedy or something I wished he’d gotten figured out sooner for my sake. In this hypothetical scenario, if it somehow managed to make us incompatible as married partners we’d deal with it but people have gotten divorced for much worse reasons before. The worst part for me would be worrying if he’d been miserable during our marriage, because I love him and would hate for that to be his experience of our time together.
It’s really hard to imagine because AFAIK we’re both cis but personally I’d probably prefer to stay married to my spouse even if he changed his gender identity. I mean he’s still the same person I married and we still love the same things and have a wonderful life and child together. I dunno, maybe it wouldn’t work out in the end but I sure as hell wouldn’t be mad at him for something he couldn’t change.
Anyways, my point is you don’t have to assume that your relationships with cis people will all get blown up if you do happen to be trans. I appreciate the urge to have your ducks all in a row before embarking on significant life events but the truth is that marriage and adulthood is super messy anyways. If you marry someone and have a kid with them the odds are good you will have all sorts of chaotic events to deal with- physical illnesses, mental illnesses, kid stress or illness, weight gain or loss, money trouble, job changes, changes in personality with age, the list goes on and on. The trick to being happily married is rolling with the changes, working hard at your partnership, and being committed to your partner, not having it all perfectly lined up at the start.