Strangely enough, I’m around the same as as the OP and about to enter the same sort of situation, although I am hoping it won’t last six months. My sister decided to move in with her fiance, so that left me either finding a place of my own, covering rent for a two bedroom apartment until I can find a roommate, or suck it up and crash with my parents for a couple of months until things settle down and I can find an appropriate place to move. (Finding a place now is pretty much impossible since I have vacation plans from the end of the month until the middle of the next)
The difference is, my parents aren’t the complete assholes you portray yours to be. My mom and I get along better when we don’t live together, but I don’t get along with my dad at all whether we live together or not; we’re both stubborn explosive people, and while he doesn’t recognize it, I do. Yet, it doesn’t help much when we get into arguments because there’s such a huge history behind us and where I can say “let’s just agree to disagree” with others I have heated conversations with, the ones with my dad accumulate until we’re screaming, throwing things, and slamming doors. I still remember when I was in fourth grade, I put a lot of effort into making this Egyptian pyramid out of paper and crafted a little tomb out of cardboard. Then when my dad got home from work, he took a look at it and stomped it into pieces because it was creepy and he didn’t want that kind of thing in the house. I know things like that were a long time ago, and I should have let that grudge go already, but things like that don’t slip from people’s consciousness when it paints vivid characterization of the person he is. I can accept that we’re all adults now, but I’m wary still because if I have children, is that how he’s going to treat them too?
Anyway, I’m not going to be under delusions that my dad will treat me as an adult tenant in the next couple of months, although I will be paying them rent. The parent-child dynamic just doesn’t work out that way, no matter how old everyone gets. What I do know is that this is temporary, and as soon as I am back from my vacation, I am going to do a full search, find a suitable place to live, and not be at the mercy of my parents’ rules. It wasn’t so long ago that I remember my first time leaving the nest. It had gone up to a boiling point with my dad and I kept saying things like “If you leave so abruptly, they’ll hate you and never speak to you again” or “I just started my first full time job, what if I get fired?” or “It’s too hard to pay my own rent, my own utilities, and buy my own groceries” but then it boiled down to “What is more important? Letting them keep their power and control, or leaving for the sake of my mental health?” That was easy once I knew the right question to ask myself. Living away from them was scary at first, but definitely worth it.
Anyway, my point is, as someone who has been there and will be there again very soon, if your mental health is suffering from your situation, find a way to change it. You can’t change your parents so either change yourself, or change your situation. Sure, you can whine about it to let off some steam, but in the end, you have to do something. Take action and responsibility for your own life.